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# C.5.1 Overview

(February 4, 2022)

BASIS

BASIS
Specifies the electronic basis sets to be used.
TYPE:
STRING
DEFAULT:
No default basis set
OPTIONS:
General, Gen User defined (basis keyword required). Symbol Use standard basis sets as per Chapter 8. Mixed Use a mixture of basis sets (see Chapter 8). RECOMMENDATION: Consult literature and reviews to aid your selection. CONCENTRIC_REF_BASIS CONCENTRIC_REF_BASIS Specify the projection basis (PB) in the concentric localization procedure TYPE: STRING DEFAULT: NONE OPTIONS: Parsed in the same way as BASIS; if unspecified, the working basis (WB) will be used as PB. RECOMMENDATION: WB is usually a good choice; a smaller basis can chosen with caution to further reduce the computational cost. CONCENTRIC_VIRTS_ZETA CONCENTRIC_VIRTS_ZETA Specify the size of the truncated virtual space TYPE: INTEGER DEFAULT: 2 OPTIONS: $m$ The total number of the CL-truncated virtuals is $m\times n_{\text{occ}}^{\text{active}}$ RECOMMENDATION: Use the default; set it to a larger value if higher accuracy is requested. CONCENTRIC_VIRTS CONCENTRIC_VIRTS Use the concentric localization (CL) scheme to truncate the virtual space TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: TRUE Use the CL scheme to truncate the virtual space FALSE Leave the virtual space untruncated RECOMMENDATION: Use CL truncation for WFT-in-DFT calculations. CVS_IP_ALPHA CVS_IP_ALPHA Sets the number of ionized target states derived by removing $\alpha$ electron (M${}_{s}=-{{1}\over{2}}$). TYPE: INTEGER/INTEGER ARRAY DEFAULT: 0 Do not look for any IP/$\alpha$ states. OPTIONS: $[i,j,k\ldots]$ Find $i$ ionized states in the first irrep, $j$ states in the second irrep etc. RECOMMENDATION: None CVS_IP_BETA CVS_IP_BETA Sets the number of ionized target states derived by removing $\beta$ electron (M${}_{s}$=${{1}\over{2}}$, default for CVS-IP). TYPE: INTEGER/INTEGER ARRAY DEFAULT: 0 Do not look for any IP/$\beta$ states. OPTIONS: $[i,j,k\ldots]$ Find $i$ ionized states in the first irrep, $j$ states in the second irrep etc. RECOMMENDATION: None CVS_IP_STATES CVS_IP_STATES Sets the number of core-ionized states to find. By default, $\beta$ electron will be removed. TYPE: INTEGER/INTEGER ARRAY DEFAULT: 0 Do not look for any IP states. OPTIONS: [i,j,k…] Find $i$ ionized states in the first irrep, $j$ states in the second irrep etc. RECOMMENDATION: None DIRECT_DIAG DIRECT_DIAG Perform direct diagonalization to obtain all the NEO excitation energies. TYPE: INTEGER DEFAULT: 0 Use Davidson algorithm. OPTIONS: 1 Do the direct diagonalization. 0 Use Davidson algorithm. RECOMMENDATION: Only use this option when Davidson solutions are not stable. DISTORT DISTORT Specifies whether to apply pressure or external force to a chemical system TYPE: LOGICAL DEFAULT: False OPTIONS: False Do not use pressure or force True Use pressure or force RECOMMENDATION: Set to true to apply pressure or force. EDA2_MOM EDA2_MOM Perform ALMO-EDA calculation with non-aufbau electronic configurations using MOM TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: FALSE Standard ALMO-EDA calculation TRUE ALMO-EDA for non-aufbau states RECOMMENDATION: None EDA_ALIGN_FRGM_SPIN EDA_ALIGN_FRGM_SPIN Turn on the fragment spin alignment procedure TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Do not performed the spin alignment procedure (turned on by default in unrestricted cases) 1 Perform fragment spin alignment; use GDM for the polarization step preceding the MOM calculations 2 Perform fragment spin alignment; use GDM and perform stability analysis for the polarization step RECOMMENDATION: Use 1 or 2 when the radical is of highly symmetric structure EDA_NOCV EDA_NOCV Perform the NOCV analysis and plot the significant NOCVs TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Do not perform NOCV analysis 1 Plot NOCV pair contributions to density deformation 2 Plot both NOCV pair contribution to density deformation and NOCV orbitals RECOMMENDATION: None EDA_PLOT_DIFF_DEN EDA_PLOT_DIFF_DEN Plot changes in electron density due to POL and CT TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: FALSE Do not make EDD plots TRUE Make EDD plots RECOMMENDATION: None EIGSLV_METH EIGSLV_METH Control the method for solving the ALMO-CIS eigen-equation TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Explicitly build the Hamiltonian then diagonalize (full-spectrum). 1 Use the Davidson method (currently only available for restricted cases). RECOMMENDATION: None ENV_METHOD ENV_METHOD Specify the low-level theory in a projection-based embedding calculation TYPE: STRING DEFAULT: NONE OPTIONS: Parsed in the same way asrem variable “METHOD
RECOMMENDATION:
A mean-field method (pure or hybrid density functional) should be chosen.

ESP_EFIELD

ESP_EFIELD
Triggers the calculation of ESP and/or E-field at nuclear positions or on a given grid of points
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Compute ESP only 1 Compute both ESP and electric field 2 Compute electric field only
RECOMMENDATION:
None

EX_EDA

EX_EDA
Perform an ALMO-EDA calculation with one or more fragments excited.
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
TRUE Perform EDA with excited-state molecule(s) taken into account. FALSE
RECOMMENDATION:
None

FIXING_V_EMBED

FIXING_V_EMBED
Invoke the linearized approximation for the energy functional used for embedding calculations
TYPE:
BOOLEAN
DEFAULT:
TRUE
OPTIONS:
TRUE Use the linearized approximation for energy functional [Eq. (11.99)] FALSE Use the original energy functional [Eq. (11.93)]
RECOMMENDATION:
Use the default to achieve savings in computational costs

FODFT_DONOR

FODFT_DONOR
Specify the donor fragment in FODFT calculation
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
1 First fragment as donor 2 Second fragment as donor
RECOMMENDATION:
With FODFT_METHOD = 1, the charged fragment needs to be the donor fragment

FODFT_METHOD

FODFT_METHOD
Specify the flavor of FODFT method
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
1 FODFT($\mathrm{2n-1}$)@$D^{+}A$ (HT) / FODFT($\mathrm{2n+1}$)@$D^{-}A$ (ET) 2 FODFT($\mathrm{2n}$)@$DA$ 3 FODFT($\mathrm{2n-1}$)@$DA$ (HT) / FODFT($\mathrm{2n+1}$)@$D^{-}A^{-}$ (ET)
RECOMMENDATION:
The default approach shows the best overall performance

FRAG_DIABAT_DOHT

FRAG_DIABAT_DOHT
Specify whether hole or electron transfer is considered
TYPE:
BOOLEAN
DEFAULT:
TRUE
OPTIONS:
TRUE Do hole transfer FALSE Do electron transfer
RECOMMENDATION:
Need to be specified for POD and FODFT calculations

FRAG_DIABAT_METHOD

FRAG_DIABAT_METHOD
Specify fragment based diabatization method
TYPE:
STRING
DEFAULT:
NONE
OPTIONS:
ALMO_MSDFT Perform ALMO(MSDFT) diabatization POD Perform projection operator diabatization (the original method) POD2_L Perform POD2 with Löwdin orthogonalization POD2_GS Perform POD2 with Grad-Schmidt orthogonalization ESID The energy-split-in-dimer method,1143 which is equivalent to the FMO approach introduced in Section 10.14.2.5 FODFT Calculate electronic coupling using fragment orbital DFT
RECOMMENDATION:
NONE

FRAG_DIABAT_PRINT

FRAG_DIABAT_PRINT
Specify the print level for fragment based diabatization calculations
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 No additional prints $\geq 1$ Print additional details
RECOMMENDATION:
Use the default unless debug information is needed

GAP_TOL

GAP_TOL
HOMO/LUMO gap threshold to control whether to shift the diagonal elements of the virtual block of the Fock matrix or not. If the HOMO/LUMO gap is less than this threshold, at a given SCF iteration, then the diagonal elements of the virtual block of the Fock matrix are shifted. Otherwise no level-shift is applied.
TYPE:
INTEGER
DEFAULT:
300
OPTIONS:
User-defined
RECOMMENDATION:
The input number must be an integer between 0 and 9999. The actual threshold is equal to GAP_TOL divided by 1000, in Hartree. The default value is provided to make the level-shifting calculation run and should not be taken as optimal for any specific problem. Trial and error may be required to find the optimal threshold. Larger values of GAP_TOL generally lead to level-shifting being used more frequently during the SCF convergence process.

GEN_SCFMAN_EMBED

GEN_SCFMAN_EMBED
Run a projection-based embedding calculation using the implementation based onGEN_SCFMAN
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
TRUE Perform a projection-based embedding calculation FALSE Do not perform an embedding calculation
RECOMMENDATION:
None

GUESS_GRID

GUESS_GRID
Specifies the type of grid to use for SAP guess generation. The options are the same as those of the $rem variable XC_GRID. TYPE: INTEGER DEFAULT: 1 OPTIONS: 0 Use SG-0 for H, C, N, and O; SG-1 for all other atoms. $n$ Use SG-$n$ for all atoms, $n=1,2$, or 3 $XY$ A string of two six-digit integers $X$ and $Y$, where $X$ is the number of radial points and $Y$ is the number of angular points where possible numbers of Lebedev angular points, which must be an allowed value from Table 5.2 in Section 5.5. $-XY$ Similar format for Gauss-Legendre grids, with the six-digit integer $X$ corresponding to the number of radial points and the six-digit integer $Y$ providing the number of Gauss-Legendre angular points, $Y=2N^{2}$. RECOMMENDATION: Larger grids may be required if the SAP guess is poor. JOBTYPE JOBTYPE Specifies the calculation. TYPE: STRING DEFAULT: Default is single-point, which should be changed to one of the following options. OPTIONS: OPT Equilibrium structure optimization. TS Transition structure optimization is currently not available in NEO. RPATH Intrinsic reaction path following is currently not available in NEO. RECOMMENDATION: Application-dependent. Always use SYM_IGNORE = 1 with geometry optimization. LEVEL_SHIFT LEVEL_SHIFT Determine whether to invoke level-shifting or not together with DIIS. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TURE, FALSE RECOMMENDATION: Use TRUE if level-shifting is necessary to accelerate SCF convergence. LSHIFT LSHIFT Constant shift applied to all diagonal elements of the virtual block of the Fock matrix. TYPE: INTEGER DEFAULT: 200 OPTIONS: User-defined RECOMMENDATION: The input number must be an integer between 0 and 9999. The actual shift is equal to GAP_TOL divided by 1000, in Hartree. The default value is provided to make the level-shifting calculation run and should not be taken as optimal for any specific problem. Trial and error may be required to find the optimal threshold. Larger level shifts make the SCF process more stable but also slow down convergence, thus requiring more SCF cycles. MAX_DP_CYCLES MAX_DP_CYCLES The maximum number of SCF iterations with damping when SCF_ALGORITHM = DP_DIIS and DP_GDM. See also THRESH_DP_SWITCH. TYPE: INTEGER DEFAULT: 3 OPTIONS: 1 Only a single SCF step with damping, and no damping for the remaining SCF steps. $n$ $n$ SCF iterations with damping before turning damping off. RECOMMENDATION: Increase this number if strong fluctuation continues after damping is turned off. MAX_LS_CYCLES MAX_LS_CYCLES The maximum number of DIIS iterations with level-shifting when SCF_ALGORITHM = LS_DIIS. See also THRESH_LS_SWITCH. TYPE: INTEGER DEFAULT: MAX_SCF_CYCLES OPTIONS: 1 Only a single DIIS step with level-shifting, and no level-shifting for the remaining DIIS steps. $n$ $n$ DIIS iterations with level-shifting before turning level-shifting off. RECOMMENDATION: None MAX_SCF_CYCLES MAX_SCF_CYCLES Controls the maximum number of SCF iterations permitted. TYPE: INTEGER DEFAULT: 50 OPTIONS: $n$ $n>0$ User-selected. RECOMMENDATION: Increase for slowly converging systems such as those containing transition metals. METHOD METHOD Specifies the exchange-correlation functional. TYPE: STRING DEFAULT: No default OPTIONS: NAME Use METHOD = NAME, where NAME is one of the following: HF for Hartree-Fock theory; one of the DFT methods listed in Section 5.3.5.; RECOMMENDATION: In general, consult the literature to guide your selection. Our recommendations for DFT are indicated in bold in Section 5.3.5. MOM_METHOD MOM_METHOD Determines the target orbitals with which to maximize the overlap on each SCF cycle. TYPE: INTEGER DEFAULT: MOM OPTIONS: MOM Maximize overlap with the orbitals from the previous SCF cycle. IMOM Maximize overlap with the initial guess orbitals. RECOMMENDATION: If appropriate guess orbitals can be obtained, then IMOM can provide more reliable convergence to the desired solution.60 MSDFT_METHOD MSDFT_METHOD Specify the scheme for ALMO(MSDFT) TYPE: INTEGER DEFAULT: 2 OPTIONS: 1 The original MSDFT scheme [Eq. (10.134)] 2 The ALMO(MSDFT2) approach [Eq. (10.137)] RECOMMENDATION: Use the default method. Note that the method will be automatically reset to 1 if a meta-GGA functional is requested. MSDFT_PINV_THRESH MSDFT_PINV_THRESH Set the threshold for pseudo-inverse of the interstate overlap TYPE: INTEGER DEFAULT: 4 OPTIONS: $n$ Set the threshold to 10${}^{-n}$ RECOMMENDATION: Use the default value NDAMP NDAMP Determine the mixing coefficient. $\alpha$ = NDAMP/100. TYPE: INTEGER DEFAULT: 75 OPTIONS: User-defined. Integers between 0 and 100. RECOMMENDATION: Increase NDAMP if strong fluctuations happen during the SCF process. NEO_BASIS_LIN_DEP_THRESH NEO_BASIS_LIN_DEP_THRESH This keyword is used to set the liner dependency threshold for nuclear basis sets. It is defined as $10^{-\mathrm{NEO\_BASIS\_LIN\_DEP\_THRESH}}$. TYPE: DOUBLE DEFAULT: 5.0 OPTIONS: User-defined RECOMMENDATION: No recommendation. NEO_EPC NEO_EPC Specifies the electron-proton correlation functional. TYPE: STRING DEFAULT: No default OPTIONS: NAME Use NEO_EPC = NAME, where NAME can be either epc172 or epc19. RECOMMENDATION: Consult the NEO literature to guide your selection. NEO_E_CONV NEO_E_CONV Energy convergence criteria in the NEO-SCF calculations so that the difference in energy between electronic and protonic iterations is less than $10^{-\mathrm{NEO\_E\_CONV}}$. TYPE: INTEGER DEFAULT: 8 OPTIONS: User-defined RECOMMENDATION: Tighter criteria for geometry optimization are recommended. NEO_ISOTOPE NEO_ISOTOPE Enable calculations of different types of isotopes. Only one type of isotope is allowed at present. TYPE: INTEGER DEFAULT: 1 Default is the proton isotope. OPTIONS: 1 This NEO calculation is using proton isotope. 2 This NEO calculation is using deuterium isotope. 3 This NEO calculation is using tritium isotope. RECOMMENDATION: Refer to the NEO literature for the best performance on the isotope effects calculations. NEO_N_SCF_CONVERGENCE NEO_N_SCF_CONVERGENCE NEO-SCF is considered converged when the nuclear wave function error is less that $10^{-\mathrm{NEO\_N\_SCF\_CONVERGENCE}}$. TYPE: INTEGER DEFAULT: 7 OPTIONS: User-defined RECOMMENDATION: None. NEO_PURECART NEO_PURECART This keyword is used to specify Cartesian or spherical Gaussians for nuclear basis functions. TYPE: INTEGER DEFAULT: 2222 OPTIONS: User-defined RECOMMENDATION: Default are Cartesian Gaussians. 1111 would define spherical Gaussians similar to keyword PURECART. Current NEO calculations do not support Cartesian electronic or nuclear basis sets with h angular momentum. NEO_VPP NEO_VPP Remove $J-K$ terms from the nuclear Fock matrix and the corresponding kernel terms for NEO excited state methods for the case of one quantum proton. TYPE: INTEGER DEFAULT: 0 OPTIONS: 1 Enable this option. 0 Disable this option. RECOMMENDATION: Use this only in the case of one quantum hydrogen. NEO NEO Enable a NEO-SCF calculation. TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: TRUE Enable a NEO-SCF calculation. FALSE Disable a NEO-SCF calculation. RECOMMENDATION: Set to TRUE if desired. POD_MULTI_PAIRS POD_MULTI_PAIRS Calculate the couplings between multiple pairs of donor and acceptor orbitals in POD TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: TRUE Calculate the couplings between multiple pairs of orbitals FALSE Only calculate the D(HOMO)–A(HOMO) coupling (for HT) or D(LUMO)–A(LUMO) coupling (for ET) RECOMMENDATION: None POD_WINDOW POD_WINDOW Specify the number of donor and acceptor orbitals when couplings between multiple pairs are requested TYPE: INTEGER DEFAULT: 5 OPTIONS: $n$ Including $n$ frontier occupied orbitals (from $\mathrm{HOMO}-n+1$ to HOMO) and $n$ frontier virtual orbitals (from LUMO to $\mathrm{LUMO}+n-1$) for both donor and acceptor RECOMMENDATION: None RR_NO_NORMALISE RR_NO_NORMALISE Controls whether frequency job calculates resonance-Raman intensities TYPE: LOGICAL DEFAULT: False OPTIONS: False Normalise RR intensities True Doesn’t normalise RR intensities RECOMMENDATION: False SCFMI_MOM SCFMI_MOM Perform an SCFMI calculation with non-aufbau electronic configurations using MOM TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: FALSE Standard SCFMI calculation TRUE SCFMI calculation with MOM RECOMMENDATION: None SCF_ALGORITHM SCF_ALGORITHM Algorithm used for converging the SCF. TYPE: STRING DEFAULT: DIIS Pulay DIIS. OPTIONS: DIIS Pulay DIIS. DM Direct minimizer. DIIS_DM Uses DIIS initially, switching to direct minimizer for later iterations (See THRESH_DIIS_SWITCH, MAX_DIIS_CYCLES). DIIS_GDM Use DIIS and then later switch to geometric direct minimization (See THRESH_DIIS_SWITCH, MAX_DIIS_CYCLES). GDM Geometric Direct Minimization. RCA Relaxed constraint algorithm RCA_DIIS Use RCA initially, switching to DIIS for later iterations (see THRESH_RCA_SWITCH and MAX_RCA_CYCLES described later in this chapter) ROOTHAAN Roothaan repeated diagonalization. RECOMMENDATION: In the NEO methods, the GDM procedure is recommended. SCF_CONVERGENCE SCF_CONVERGENCE NEO-SCF is considered converged when the electronic wave function error is less that $10^{-\mathrm{SCF\_CONVERGENCE}}$. Adjust the value of THRESH at the same time. (Starting with Q-Chem 3.0, the DIIS error is measured by the maximum error rather than the RMS error as in earlier versions.) TYPE: INTEGER DEFAULT: 5 For single point energy calculations. 8 For geometry optimizations. OPTIONS: User-defined RECOMMENDATION: None. SET_CISGUES SET_CISGUES Controls how to generate the initial guess excitation vectors in CIS/TDA/RPA calculations. TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Generate N (no. of roots requested) occupied$\to$virtual single orbital transitions according to their orbital energy difference order (from low to high). This is the common scenario. 1 Generate N-1 occupied$\to$virtual single orbital transitions according to their orbital energy difference order (from low to high), and generate another guess excitation vector consist of all the remaining single orbital transitions in the occupied$\to$virtual transition space with equal weights. 2 Generate N occupied/virtual single orbital transitions according to their orbital energy difference order (from low to high), and generate one more guess excitation vector consist of all the remaining single orbital transitions in the occupied$\to$virtual transition space with equal weights. RECOMMENDATION: The default setting should work for most of the cases. However, when the no. of roots is small, in some CIS/TDA/RPA calculations low energy excited states could be missing. The options SET_CISGUES = 1 or 2 may remedy this root missing issue by sampling more vectors in the transition space. Setting SET_CISGUES = 1 or 2 may take more cycles to converge in the Davidson iteration, but the results are expected to be more reliable. Currently SET_CISGUES = 1 or 2 are not supported in SF-XCIS calculations. Setting TRNSS = TRUE also disables the setting of SET_CISGUES. SET_ROOTS SET_ROOTS Sets the number of NEO excited state roots to find by Davidson or display the number of roots obtained by direct diagonalization. TYPE: INTEGER DEFAULT: 0 Do not look for any excited states. OPTIONS: $n$ $n>0$ Looks for $n$ NEO excited states. RECOMMENDATION: None SET_RPA SET_RPA Do a NEO-TDDFT or NEO-TDHF calculation. TYPE: LOGICAL/INTEGER DEFAULT: FALSE OPTIONS: FALSE Do a NEO-TDA or NEO-CIS calculation. TRUE Do a NEO-TDDFT or NEO-TDHF calculation. RECOMMENDATION: Consult the NEO literature to guide your selection. SPADE_PARTITION SPADE_PARTITION Use the SPADE approach to determine the initial set of embedded (active) orbitals TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: TRUE Use SPADE to partition the occupied space FALSE Use the Pipek-Mezey localization + Mulliken population to assign occupied orbitals RECOMMENDATION: Use SPADE if a significant gap in the spectrum of singular values can be detected. THRESH_DP_SWITCH THRESH_DP_SWITCH The threshold for turning off damping in SCF iterations is $10^{-\mbox{{\small THRESH\_DP\_SWITCH}}}$ when SCF_ALGORITHM is set to DP_DIIS or DP_GDM. See also MAX_DP_CYCLES. TYPE: INTEGER DEFAULT: 2 OPTIONS: User-defined. RECOMMENDATION: None THRESH_LS_SWITCH THRESH_LS_SWITCH The threshold for turning off level-shifting in DIIS is $10^{-\mbox{{\small THRESH\_LS\_SWITCH}}}$ when SCF_ALGORITHM is set to LS_DIIS. See also MAX_LS_CYCLES. TYPE: INTEGER DEFAULT: 4 OPTIONS: User-defined. RECOMMENDATION: None UNRESTRICTED UNRESTRICTED Controls the use of restricted or unrestricted orbitals. TYPE: LOGICAL DEFAULT: FALSE Closed-shell systems. TRUE Open-shell systems. OPTIONS: FALSE Constrain the spatial part of the alpha and beta orbitals to be the same. TRUE Do not Constrain the spatial part of the alpha and beta orbitals. RECOMMENDATION: The ROHF method is not available. Note that for unrestricted calculations on systems with an even number of electrons it is usually necessary to break $\alpha$/$\beta$ symmetry in the initial guess, by using SCF_GUESS_MIX or providing$occupied information (see Section 4.4 on initial guesses).

VFB_CTA

VFB_CTA
Use the Variational Forward-Backward (VFB) approach to obtain “one-way” CT PESs.
TYPE:
STRING
DEFAULT:
NONE
OPTIONS:
FORWARD Allow 1$\rightarrow$2 CT only (1 and 2 are two fragments). BACKWARD Allow 2$\rightarrow$1 CT only.
RECOMMENDATION:
None

XC_GRID

XC_GRID
Specifies the type of grid to use for DFT calculations.
TYPE:
INTEGER
DEFAULT:
Functional-dependent; see Table 5.3.
OPTIONS:
0 Use SG-0 for H, C, N, and O; SG-1 for all other atoms. $n$ Use SG-$n$ for all atoms, $n=1,2$, or 3 $XY$ A string of two six-digit integers $X$ and $Y$, where $X$ is the number of radial points and $Y$ is the number of angular points where possible numbers of Lebedev angular points, which must be an allowed value from Table 5.2 in Section 5.5. $-XY$ Similar format for Gauss-Legendre grids, with the six-digit integer $X$ corresponding to the number of radial points and the six-digit integer $Y$ providing the number of Gauss-Legendre angular points, $Y=2N^{2}$.
RECOMMENDATION:
Use the default unless numerical integration problems arise. Larger grids may be required for optimization and frequency calculations.

FRZN_OPT

FRZN_OPT
Controls whether the job uses zeroed Hessian technique in the frequency calculations
TYPE:
LOGICAL
DEFAULT:
False
OPTIONS:
False Do not use the zeroed out Hessian True Use the zeroed out Hessian
RECOMMENDATION:
False

FRZ_ATOMS

FRZ_ATOMS
Controls the number of frozen atoms
TYPE:
INTEGER
DEFAULT:
No default
OPTIONS:
User defined
RECOMMENDATION:
None

HARM_FORCE

HARM_FORCE
Sets the force constant for harmonic confiner
TYPE:
INTEGER
DEFAULT:
No default
OPTIONS:
User defined
RECOMMENDATION:
None

HARM_OPT

HARM_OPT
Controls whether the job uses confining potentials
TYPE:
LOGICAL
DEFAULT:
False
OPTIONS:
False Do not use the potential True Use the potential
RECOMMENDATION:
False

HOATOMS

HOATOMS
Controls the number of confined atom
TYPE:
INTEGER
DEFAULT:
No default
OPTIONS:
User defined
RECOMMENDATION:
None

CLENSHAW_NGRID

CLENSHAW_NGRID
Number of grid points for the Curtis-Clenshaw quadrature.
TYPE:
INTEGER
DEFAULT:
40
OPTIONS:

RECOMMENDATION:
Use default.

COMPLEX_EXPONENTS

COMPLEX_EXPONENTS
Enable a non-Hermitian calculation with CBFs.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE Perform a non-Hermitian calculation with CBFs
RECOMMENDATION:
Set to TRUE if a non-Hermitian calculation using CBFs is desired.

COMPLEX_METSCF

COMPLEX_METSCF
Specify the NH-SCF solver
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
0 Roothaan iterations 1 DIIS 3 ADIIS 21 Newton-MINRES
RECOMMENDATION:
Use the default (DIIS).

COMPLEX_N_ELECTRON

COMPLEX_N_ELECTRON
TYPE:
INTEGER
DEFAULT:
0 Perform the non-Hermitian calculation on $N$-electrons
OPTIONS:
$n$ Perform the non-Hermitian calculation on an $N+n$ electron system
RECOMMENDATION:
None

COMPLEX_SCF_GUESS

COMPLEX_SCF_GUESS
Specify the NH-SCF guess
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Use a guess from a static-exchange calculation 1 Read real-basis MO coefficients 2 Read real-basis density matrix 1000 Read guess from a previous calculation
RECOMMENDATION:
Use a guess from a static exchange calculation. Note that for temporary anions, this requires the specification of COMPLEX_TARGET.

COMPLEX_SCF

COMPLEX_SCF
Perform a non-Hermitian SCF calculation with CBFs
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not perform an NH-SCF calculation 1 Perform a restricted NH-SCF calculation 2 Perform an unrestricted NH-SCF calculation 3 Perform a restricted, open-shell NH-SCF calculation
RECOMMENDATION:
None

COMPLEX_SPIN_STATE

COMPLEX_SPIN_STATE
Spin state for non-Hermitian calculation
TYPE:
INTEGER
DEFAULT:
1 Singlet
OPTIONS:
$2S+1$ A state of spin $S$
RECOMMENDATION:
None

COMPLEX_STATIC_EXCHANGE

COMPLEX_STATIC_EXCHANGE
Perform a CBF static-exchange calculation.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE Perform a static exchange calculation FALSE Do not perform a static exchange calculation
RECOMMENDATION:
Set to TRUE if a static-exchange calculation is desired.

COMPLEX_TARGET

COMPLEX_TARGET
Specify the orbital index to be occupied for a temporary anion
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
$n$ Orbital index (starting at zero) for the additional electron
RECOMMENDATION:
$n$ should always be greater than $N_{\text{occ}}-1$.

NOCIS

NOCIS
Run a NOCIS calculation
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
False Do not run a NOCIS calculation. True Run a NOCIS calculation.
RECOMMENDATION:
This variable must be set to true to run a NOCIS or a 1C-NOCIS calculation.

NOCI_DETGEN

NOCI_DETGEN
Control how the multiple determinants for NOCI are created.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Use only the initial reference determinants. 1 Generate CIS excitations from each reference determinant. 2 Generate all FCI excitations from each reference determinant. 3 Generate $n$ multiple determinants using SCF metadynamics, where $n$ is specified using SCF_SAVEMINIMA = $n$. 4 Generate all CAS excitations from each reference determinant, where the active orbitals are specified using the $active_orbitals input section. RECOMMENDATION: By default, these multiple determinants are optimized at the SCF level before running NOCI. This behavior can be turned off using by specifying SKIP_SCFMAN = TRUE. NOCI_NEIGVAL NOCI_NEIGVAL The number of NOCI eigenvalues to be printed. TYPE: INTEGER DEFAULT: 10 OPTIONS: $n$ Positive integer RECOMMENDATION: Increase this to print progressively higher NOCI energies. NOCI_REFGEN NOCI_REFGEN Control how the initial reference determinants are created. TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Generate initial reference determinant from a single SCF calculation. 1 Read (multiple) initial reference determinants from a previous calculation. RECOMMENDATION: The specific reference determinants to be read from a previous calculation can be indicated using SCF_READMINIMA. NUM_REF NUM_REF Set the number of atoms (references) to be included in the excitation calculation TYPE: Integer DEFAULT: None OPTIONS: $n$ Positive integer RECOMMENDATION: This variable determines the number of references for the calculation. As an example, for the oxygen K-edge in CO${}_{2}$, the number of references would be would be 2 (two oxygen atoms), whereas for carbon it would be 1 (one carbon atom). ONE_CENTER ONE_CENTER Run a 1C-NOCIS calculation TYPE: LOGICAL DEFAULT: FALSE OPTIONS: False Run a NOCIS calculation. True Run a 1C-NOCIS calculation. RECOMMENDATION: This variable must be set to true to run a 1C-NOCIS calculation, and NOCIS must be set to true as well. ORB_OFFSET ORB_OFFSET Determine the starting orbital for a NOCIS/STEX/1C-NOCIS calculation TYPE: Integer DEFAULT: None OPTIONS: $n$ Non-negative integer RECOMMENDATION: This variable determines the starting orbital for the calculation. As an example, for the oxygen K-edge in CO${}_{2}$, the starting orbital would be 0, whereas for carbon it would be 2. REL_X2C_FD_DISPLACEMENT REL_X2C_FD_DISPLACEMENT Controls finite difference step for calulating W TYPE: INTEGER DEFAULT: 100 OPTIONS: $n$ Set finite difference step to $n\times 10^{-6}$ RECOMMENDATION: None REL_X2C REL_X2C Enables X2C scalar relativistic calculation TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Perform a regular, non-relativistic SCF calculation 1 Perform a scalar relativistic X2C calculation RECOMMENDATION: Set to 1 if a scalar relativistic X2C calculation is desired. SCF_EESCALE_ARG SCF_EESCALE_ARG Control the phase angle of the complex $\lambda$ electron-electron scaling. TYPE: INTEGER DEFAULT: $00000$ meaning $0.0000$ OPTIONS: $abcde$ corresponding to $a.bcde$ RECOMMENDATION: A complex phase angle of $00500$, meaning $0.0500$, is usually sufficient to follow a solution safely past the Coulson-Fischer point and onto its complex holomorphic counterpart. SCF_EESCALE_MAG SCF_EESCALE_MAG Control the magnitude of the $\lambda$ electron-electron scaling. TYPE: INTEGER DEFAULT: $10000$ meaning $1.0000$ OPTIONS: $abcde$ corresponding to $a.bcde$ RECOMMENDATION: For holomorphic Hartree-Fock orbitals, only the magnitude of the input is used, while for real Hartree-Fock orbitals, the input sign indicates the sign of $\lambda$. SCF_HOLOMORPHIC SCF_HOLOMORPHIC Turn on the use of holomorphic Hartree-Fock orbitals. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: FALSE Holomorphic Hartree-Fock is turned off TRUE Holomorphic Hartree-Fock is turned on. RECOMMENDATION: If TRUE, holomorphic Hartree-Fock complex orbital coefficients will always be used. If FALSE, but COMPLEX = TRUE, complex Hermitian orbitals will be used. STEX STEX Run a STEX calculation TYPE: LOGICAL DEFAULT: FALSE OPTIONS: False Do not run a STEX calculation. True Run a STEX calculation. RECOMMENDATION: This variable must be set to true to run a STEX calculation. NOCIS cannot be set to true. USE_LIBNLQ USE_LIBNLQ Turn on the use of LIBNLQ for calculating nonlocal correlation funcitonal. TYPE: LOGICAL DEFAULT: True For VV10. FALSE For all other nonlocal funcitonals. OPTIONS: False True RECOMMENDATION: Use the default USE_LIBNOCI USE_LIBNOCI Turn on the use of libnoci for running NOCI calculations. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: False Do not use libnoci (uses original Q-Chem implementation). True Use the libnoci implementation. RECOMMENDATION: The$rem variables detailed below are only available in libnoci.

EDA_COVP_THRESH

EDA_COVP_THRESH
Specifies the significance above which the COVPs will be saved
TYPE:
INTEGER
DEFAULT:
5
OPTIONS:
$N$ COVPs that accounts for more than $N$% of the fragment-wise energy or charge transfer will be saved
RECOMMENDATION:
None

EDA_PCT_A

EDA_PCT_A
Perform perturbative CT analysis
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not perform perturbative CT analysis 1 Perform perturbative CT analysis
RECOMMENDATION:
Set to 1 to perform perturbative CT analysis

EDA_SAVE_COVP

EDA_SAVE_COVP
Save significant COVPs or not
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not save significant COVPs 1 Save significant COVPs
RECOMMENDATION:
To save the COVPs as an fchk file, GUI = 2 also has to be set

EDA_VCT_A

EDA_VCT_A
Perform non-perturbative CT analysis
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not perform non-perturbative CT analysis 1 Perform non-perturbative CT analysis.
RECOMMENDATION:
Set to 1 to perform non-perturbative CT analysis

GEN_SCFMAN_EDA2

GEN_SCFMAN_EDA2
Perform ALMO-EDA calculations using the GEN_SCFMAN_EDA2 driver (differing from jobs with EDA2 $>$ 0)
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not use the new ALMO-EDA framework 1 Use the new ALMO-EDA framework
RECOMMENDATION:
Set to 1 to perform non-perturbative CT analysis

PLOT_ALMO_FRZ

PLOT_ALMO_FRZ
Plot ALMOs at the frozen stage of EDA2 calculations
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE Do not plot frozen ALMOs TRUE Plot frozen ALMOs
RECOMMENDATION:
None

PLOT_ALMO_POL

PLOT_ALMO_POL
Plot ALMOs after the polarization calculation
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE Do not plot polarized ALMOs TRUE Plot polarized ALMOs
RECOMMENDATION:
None

FDIFF_STEPSIZE

FDIFF_STEPSIZE
Displacement used for calculating derivatives by finite difference.
TYPE:
INTEGER
DEFAULT:
1 Corresponding to $1.88973\times 10^{-5}$ a.u.
OPTIONS:
$n$ Use a step size of $n$ times the default value.
RECOMMENDATION:
Use the default unless problems arise.

RESPONSE_POLAR

RESPONSE_POLAR
Control the use of analytic or numerical polarizabilities.
TYPE:
INTEGER
DEFAULT:
0 or $-$1 = 0 for HF or DFT, $-$1 for all other methods
OPTIONS:
0 Perform an analytic polarizability calculation. $-$1 Perform a numeric polarizability calculation even when analytic 2nd derivatives are available.
RECOMMENDATION:
None

Controls the type of CAP/ADC calculation to be performed.
TYPE:
INTEGER
DEFAULT:
0 Do not perform a CAP/ADC calculation.
OPTIONS:
1 Perform a subspace-projected CAP/ADC calculation.
RECOMMENDATION:
Set to 1 for the computation of CAP/ADC subspace projections.

Activates the use of the CVS approximation for the calculation of CVS-ADC core-excited states.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE Activates the CVS approximation. FALSE Do not compute core-excited states using the CVS approximation.
RECOMMENDATION:
Set to TRUE, if to obtain core-excited states for the simulation of X-ray absorption spectra. In the case of TRUE, the $rem variable CC_REST_OCC has to be defined as well. ADC_C_C ADC_C_C Set the spin-opposite scaling parameter $c_{c}$ for the ADC(2) calculation. The parameter value is obtained by multiplying the given integer by $10^{-3}$. TYPE: INTEGER DEFAULT: 1170 Optimized value $c_{c}=1.17$ for ADC(2)-s or 1000 $c_{c}=1.0$ for ADC(2)-x OPTIONS: $n$ Corresponding to $n\cdot 10^{-3}$ RECOMMENDATION: Use the default. ADC_C_T ADC_C_T Set the spin-opposite scaling parameter $c_{T}$ for an SOS-ADC(2) calculation. The parameter value is obtained by multiplying the given integer by $10^{-3}$. TYPE: INTEGER DEFAULT: 1300 Optimized value $c_{T}=1.3$. OPTIONS: $n$ Corresponding to $n\cdot 10^{-3}$ RECOMMENDATION: Use the default. ADC_C_X ADC_C_X Set the spin-opposite scaling parameter $c_{x}$ for the ADC(2)-x calculation. The parameter value is obtained by multiplying the given integer by $10^{-3}$. TYPE: INTEGER DEFAULT: 1300 Optimized value $c_{x}=0.9$ for ADC(2)-x. OPTIONS: $n$ Corresponding to $n\cdot 10^{-3}$ RECOMMENDATION: Use the default. ADC_DAVIDSON_CONV ADC_DAVIDSON_CONV Controls the convergence criterion of the Davidson procedure. TYPE: INTEGER DEFAULT: $6$ Corresponding to $10^{-6}$ OPTIONS: $n\leq 12$ Corresponding to $10^{-n}$. RECOMMENDATION: Use the default unless higher accuracy is required or convergence problems are encountered. ADC_DAVIDSON_MAXITER ADC_DAVIDSON_MAXITER Controls the maximum number of iterations of the Davidson procedure. TYPE: INTEGER DEFAULT: 60 OPTIONS: $n$ Number of iterations RECOMMENDATION: Use the default unless convergence problems are encountered. ADC_DAVIDSON_MAXSUBSPACE ADC_DAVIDSON_MAXSUBSPACE Controls the maximum subspace size for the Davidson procedure. TYPE: INTEGER DEFAULT: $5\times$ the number of excited states to be calculated. OPTIONS: $n$ User-defined integer. RECOMMENDATION: Should be at least 2–4$\times$ the number of excited states to calculate. The larger the value the more disk space is required. ADC_DAVIDSON_THRESH ADC_DAVIDSON_THRESH Controls the threshold for the norm of expansion vectors to be added during the Davidson procedure. TYPE: INTEGER DEFAULT: Twice the value of ADC_DAVIDSON_CONV, but at maximum $10^{-14}$. OPTIONS: $n\leq 14$ Corresponding to $10^{-n}$ RECOMMENDATION: Use the default unless convergence problems are encountered. The threshold value $10^{-n}$ should always be smaller than the convergence criterion ADC_DAVIDSON_CONV. ADC_DENSITY_MAXITER ADC_DENSITY_MAXITER When setting ADC_DENSITY_ORDER = 4, this keyword controls the maximum number of DIIS iterations carried out in the $\Sigma(4+)$ procedure. TYPE: INTEGER DEFAULT: 1000 OPTIONS: $n$ User-defined integer. RECOMMENDATION: Use the default value. ADC_DENSITY_ORDER ADC_DENSITY_ORDER Controls the order of the ground state density used for the computation of third-order ADC matrix elements (non-CVS methods only). TYPE: INTEGER DEFAULT: 2 Use strict third-order ADC(3) schemes. OPTIONS: 3 Use a third-order ground state density computed from the IP-ADC(3) effective transition moments and the corresponding fourth order static self-energy according to the $\Sigma(4)$ scheme 4 Use an improved third-order ground state density and the corresponding improved fourth-order static self-energy computed according to the self-consistent $\Sigma(4+)$ procedure RECOMMENDATION: In case of IP-ADC(3) calculations, employing the $\Sigma(4+)$ scheme provides more accurate ionization potentials and ionized state dipole moments. ADC_DIIS_ECONV ADC_DIIS_ECONV Controls the convergence criterion for the excited state energy during DIIS. TYPE: INTEGER DEFAULT: 6 Corresponding to $10^{-6}$ OPTIONS: $n$ Corresponding to $10^{-n}$ RECOMMENDATION: None ADC_DIIS_MAXITER ADC_DIIS_MAXITER Controls the maximum number of DIIS iterations. TYPE: INTEGER DEFAULT: 50 OPTIONS: $n$ User-defined integer. RECOMMENDATION: Increase in case of slow convergence. ADC_DIIS_RCONV ADC_DIIS_RCONV Convergence criterion for the residual vector norm of the excited state during DIIS. TYPE: INTEGER DEFAULT: 6 Corresponding to $10^{-6}$ OPTIONS: $n$ Corresponding to $10^{-n}$ RECOMMENDATION: None ADC_DIIS_SIZE ADC_DIIS_SIZE Controls the size of the DIIS subspace. TYPE: INTEGER DEFAULT: 7 OPTIONS: $n$ User-defined integer RECOMMENDATION: None ADC_DIIS_START ADC_DIIS_START Controls the iteration step at which DIIS is turned on. TYPE: INTEGER DEFAULT: 1 OPTIONS: $n$ User-defined integer. RECOMMENDATION: Set to a large number to switch off DIIS steps. ADC_DIRECT ADC_DIRECT For third-order ADC methods, this keyword controls if some large intermediate tensor contractions should be carried out in advance and the result saved in memory for later use or if these quantities should be evaluated directly whenever they are encountered. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Directly evaluate some $N^{6}$-scaling tensor contractions. This will reduce the memory requirement by $\sim$10 %. FALSE Precompute all possible $N^{6}$-scaling intermediates. This will speed up ADC(3) calculations considerably (by a factor of $\sim$3 in case of ADC(3) for $N$-electron excitations and somewhat less for IP- and EA-ADC(3)). RECOMMENDATION: Use the default value unless memory is the bottleneck. ADC_DO_DIIS ADC_DO_DIIS Activates the use of the DIIS algorithm for the calculation of ADC(2) excited states. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Use DIIS algorithm. FALSE Do diagonalization using Davidson algorithm. RECOMMENDATION: None. ADC_DO_DYSON ADC_DO_DYSON Controls if Dyson orbitals are output in case of IP- and EA-ADC calculations. This keyword only takes effect when used together with STATE_ANALYSIS = TRUE. See Section. 10.2.9 for further details. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Output Dyson orbitals as cube files. FALSE Do not output Dyson orbitals. RECOMMENDATION: Set to TRUE if visualization of ionization/electron-attachment processes is desired. ADC_NGUESS_DOUBLES ADC_NGUESS_DOUBLES Controls the number of excited state guess vectors which are double excitations, two-hole-one-particle ionizations and one-hole-two-particle electron-attachments in case of ADC, IP-ADC and EA-ADC, respectively. TYPE: INTEGER DEFAULT: 0 OPTIONS: $n$ User-defined integer. RECOMMENDATION: ADC_NGUESS_SINGLES ADC_NGUESS_SINGLES Controls the number of excited state guess vectors which are single excitations, one-hole ionizations and one-particle electron-attachments in case of ADC, IP-ADC and EA-ADC, respectively. If the number of requested excited states exceeds the total number of guess vectors (singles and doubles), this parameter is automatically adjusted, so that the number of guess vectors matches the number of requested excited states. TYPE: INTEGER DEFAULT: Equals to the number of excited states requested. OPTIONS: $n$ User-defined integer. RECOMMENDATION: Increase if there are convergence problems. ADC_PRINT ADC_PRINT Controls the amount of printing during an ADC calculation. TYPE: INTEGER DEFAULT: 1 Basic status information and results are printed. OPTIONS: 0 Quiet: almost only results are printed. 1 Normal: basic status information and results are printed. 2 Debug: more status information, extended information on timings. RECOMMENDATION: Use the default. ADC_PROP_ES2ES ADC_PROP_ES2ES Controls the calculation of transition properties between excited, ionized or electron-attached states (currently only transition dipole moments and oscillator strengths). For ADC for $N$-electron excitations, this keyword also controls the computation of two-photon absorption cross-sections of excited states using the sum-over-states expression. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Calculate state-to-state transition properties. FALSE Do not compute transition properties between excited, ionized or electron-attached states. RECOMMENDATION: Set to TRUE, if state-to-state properties (ADC, IP-ADC, EA-ADC) or sum-over-states two-photon absorption cross-sections (only ADC) are required. ADC_PROP_ES ADC_PROP_ES Controls the calculation of excited, ionized or electron-attached state properties (currently only dipole moments and $\hat{r}^{2}$ expectation values). TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Calculate excited, ionized or electron-attached state properties. FALSE Do not compute state properties. RECOMMENDATION: Set to TRUE, if properties are required. ADC_PROP_TPA ADC_PROP_TPA Controls the calculation of two-photon absorption cross-sections of excited states using matrix inversion techniques. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Calculate two-photon absorption cross-sections. FALSE Do not compute two-photon absorption cross-sections. RECOMMENDATION: Set to TRUE, if to obtain two-photon absorption cross-sections. ADC_STRICT_ISR ADC_STRICT_ISR Controls how second-order ground state contributions are treated in the calculation of second- and third-order IP- and EA-ADC state properties using the second-order ISR formalism. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Scale the second-order part of the ground state contribution to one-electron properties of ionized/electron-attached states by the one-hole/one-particle character of the respective states as implied by the strict ISR derivation. FALSE Use the full second-order ground state contribution for each ionized/electron-attached state property. RECOMMENDATION: Use the default value. Both options are, however, valid second-order treatments of ionized/electron-attached state properties and should yield very similar results for states with predominant one-hole/one-particle chaaracter. ADD_CHARGED_CAGE ADD_CHARGED_CAGE Add a point charge cage of a given radius and total charge. TYPE: INTEGER DEFAULT: 0 No cage. OPTIONS: 0 No cage. 1 Dodecahedral cage. 2 Spherical cage. RECOMMENDATION: Spherical cage is expected to yield more accurate results, especially for small radii. ADIIS_INNER_CONV ADIIS_INNER_CONV Convergence criterion for the ADIIS inner loops (L-BFGS optimization of Eq. 4.43) TYPE: INTEGER DEFAULT: 12 OPTIONS: $n$ Using 10${}^{-n}$ as the convergence criterion for the ADIIS inner loops RECOMMENDATION: Use the default AFSSH AFSSH Adds decoherence approximation to surface hopping calculation. TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Traditional surface hopping, no decoherence. 1 Use augmented fewest-switches surface hopping (AFSSH). RECOMMENDATION: AFSSH will increase the cost of the calculation, but may improve accuracy for some systems. See Refs. 1092, 1095, 620 for more detail. AIFDEM_CTSTATES AIFDEM_CTSTATES Include charge-transfer-like cation/anion pair states in the AIFDEM basis. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Include CT states. FALSE Do not include CT states. RECOMMENDATION: Use if CT states are desired in the basis. AIFDEM_EMBED_RANGE AIFDEM_EMBED_RANGE Specifies the size of the QM region for charge embedding TYPE: INTEGER DEFAULT: FULL_QM OPTIONS: FULL_QM No charge embedding. 0 Treat only excited fragments with QM. $n$ Range (in Å) from excited fragments within which to treat other fragments with QM. RECOMMENDATION: The minimal threshold of zero typically maintains accuracy while significantly reducing computational time. AIFDEM_FRGM_READ AIFDEM_FRGM_READ Skips fragment SCF calculations. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Skips fragment SCF calculations, only computation of matrix elements. FALSE Regular AIFDEM calculation as specified by other$rem variables.
RECOMMENDATION:
Requires a prior calculation that computes fragment SCF data.

AIFDEM_FRGM_WRITE

AIFDEM_FRGM_WRITE
Fragment SCF calculations only.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE Only fragment SCF calculations are carried out, no computation of matrix elements. FALSE Regular AIFDEM calculation as specified by other $rem variables. RECOMMENDATION: None AIFDEM_NTOTHRESH AIFDEM_NTOTHRESH Controls how many NTOs that are retained in the exciton-site basis states. TYPE: INTEGER DEFAULT: 99 OPTIONS: $n$ Retain enough NTOs to recover $n$% of the norm of the original CIS or TDDFT vectors in Eq. (12.68). RECOMMENDATION: A threshold of $85\%$ gives a good trade-off of computational time and accuracy for organic molecules. AIFDEM_SEGEND AIFDEM_SEGEND Indicates the index of the last matrix element to be computed. TYPE: INTEGER DEFAULT: NONE OPTIONS: $n$ Last matrix element of thhe chunk to be computed. RECOMMENDATION: Needs to be used with AIFDEM_SEGSTART AIFDEM_SEGSTART AIFDEM_SEGSTART Indicates the index of the first matrix element to be computed. TYPE: INTEGER DEFAULT: NONE OPTIONS: $n$ First matrix element of the chunk to be computed. RECOMMENDATION: Needs to be used with AIFDEM_SEGEND AIFDEM_SINGFIS AIFDEM_SINGFIS Include multi-exciton states in the AIFDEM basis. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Include multi-exciton states. FALSE Do not include multi-exciton states. RECOMMENDATION: Use if multi-exciton states are desired in the basis. This option requires the use of AIFDEM_SEGSTART and AIFDEM_SEGEND in the$rem section.

AIFDEM

AIFDEM
Perform an AIFDEM calculation.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE Do not perform an AIFDEM calculation. TRUE Perform an AIFDEM calculation.
RECOMMENDATION:
False

AIMD_FICT_MASS

AIMD_FICT_MASS
Specifies the value of the fictitious electronic mass $\mu$, in atomic units, where $\mu$ has dimensions of (energy)$\times$(time)${}^{2}$.
TYPE:
INTEGER
DEFAULT:
None
OPTIONS:
User-specified
RECOMMENDATION:
Values in the range of 50–200 a.u. have been employed in test calculations; consult Ref. 454 for examples and discussion.

AIMD_INIT_VELOC_NANO_RANDOM

AIMD_INIT_VELOC_NANO_RANDOM
Uses a more precise random seed for generating random initial velocities.
TYPE:
LOGICAL
DEFAULT:
TRUE Use a more precise random seed.
OPTIONS:
FALSE Use a less precise random seed.
RECOMMENDATION:
Leave this set to TRUE unless necessary. This option determines the source of the random seed used for sampling random initial velocities when AIMD_INIT_VELOC requires such. Setting the option to FALSE will have the seed based on the system time in seconds, meaning that two otherwise identical simulations starting in the same second will produce identical initial velocities. With the option set to TRUE, such collisions are virtually impossible. The option is kept for legacy purposes. There should rarely ever be a need to set it to FALSE.

AIMD_INIT_VELOC

AIMD_INIT_VELOC
Specifies the method for selecting initial nuclear velocities.
TYPE:
STRING
DEFAULT:
None
OPTIONS:
THERMAL Random sampling of nuclear velocities from a Maxwell-Boltzmann distribution. The user must specify the temperature in Kelvin via the $rem variable AIMD_TEMP. ZPE Choose velocities in order to put zero-point vibrational energy into each normal mode, with random signs. This option requires that a frequency job to be run beforehand. QUASICLASSICAL Puts vibrational energy into each normal mode. In contrast to the ZPE option, here the vibrational energies are sampled from a Boltzmann distribution at the desired simulation temperature. This also triggers several other options, as described below. OLD Use the same initial velocities as the immediately preceding AIMD job. RESTART Use the final velocities from a previous AIMD job, reading them from disk. RECOMMENDATION: This variable need only be specified in the event that velocities are not specified explicitly in a$velocity section.

AIMD_LANGEVIN_TIMESCALE

AIMD_LANGEVIN_TIMESCALE
Sets the timescale (strength) of the Langevin thermostat
TYPE:
INTEGER
DEFAULT:
none
OPTIONS:
$n$ Thermostat timescale,asn $n$ fs
RECOMMENDATION:
Smaller values (roughly 100) equate to tighter thermostats but may inhibit rapid sampling. Larger values ($\geq 1000$) allow for more rapid sampling but may take longer to reach thermal equilibrium.

AIMD_METHOD

AIMD_METHOD
Selects an ab initio molecular dynamics algorithm.
TYPE:
STRING
DEFAULT:
BOMD
OPTIONS:
BOMD Born-Oppenheimer molecular dynamics. CURVY Curvy-steps Extended Lagrangian molecular dynamics.
RECOMMENDATION:
BOMD yields exact classical molecular dynamics, provided that the energy is tolerably conserved. ELMD is an approximation to exact classical dynamics whose validity should be tested for the properties of interest.

AIMD_MOMENTS

AIMD_MOMENTS
Requests that multipole moments be output at each time step.
TYPE:
INTEGER
DEFAULT:
0 Do not output multipole moments.
OPTIONS:
$n$ Output the first $n$ multipole moments.
RECOMMENDATION:
None

AIMD_NUCL_DACF_POINTS

AIMD_NUCL_DACF_POINTS
Number of time points to use in the dipole auto-correlation function for an AIMD trajectory
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not compute dipole auto-correlation function. $1\leq n\leq\mbox{{\small AIMD\_STEPS}}$ Compute dipole auto-correlation function for last $n$ timesteps of the trajectory.
RECOMMENDATION:
If the DACF is desired, set equal to AIMD_STEPS.

AIMD_NUCL_SAMPLE_RATE

AIMD_NUCL_SAMPLE_RATE
The rate at which sampling is performed for the velocity and/or dipole auto-correlation function(s). Specified as a multiple of steps; i.e., sampling every step is 1.
TYPE:
INTEGER
DEFAULT:
None.
OPTIONS:
$1\leq n\leq\mbox{{\small AIMD\_STEPS}}$ Update the velocity/dipole auto-correlation function every $n$ steps.
RECOMMENDATION:
Since the velocity and dipole moment are routinely calculated for ab initio methods, this variable should almost always be set to 1 when the VACF/DACF are desired.

AIMD_NUCL_VACF_POINTS

AIMD_NUCL_VACF_POINTS
Number of time points to use in the velocity auto-correlation function for an AIMD trajectory
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not compute velocity auto-correlation function. $1\leq n\leq\mbox{{\small AIMD\_STEPS}}$ Compute velocity auto-correlation function for last $n$ time steps of the trajectory.
RECOMMENDATION:
If the VACF is desired, set equal to AIMD_STEPS.

AIMD_QCT_INITPOS

AIMD_QCT_INITPOS
Chooses the initial geometry in a QCT-MD simulation.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
$0$ Use the equilibrium geometry. $n$ Picks a random geometry according to the harmonic vibrational wave function. $-n$ Generates $n$ random geometries sampled from the harmonic vibrational wave function.
RECOMMENDATION:
None.

AIMD_QCT_WHICH_TRAJECTORY

AIMD_QCT_WHICH_TRAJECTORY
Picks a set of vibrational quantum numbers from a random distribution.
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
$n$ Picks the $n$th set of random initial velocities. $-n$ Uses an average over $n$ random initial velocities.
RECOMMENDATION:
Pick a positive number if you want the initial velocities to correspond to a particular set of vibrational occupation numbers and choose a different number for each of your trajectories. If initial velocities are desired that corresponds to an average over $n$ trajectories, pick a negative number.

AIMD_SHORT_TIME_STEP

AIMD_SHORT_TIME_STEP
Specifies a shorter electronic time step for FSSH calculations.
TYPE:
INTEGER
DEFAULT:
TIME_STEP
OPTIONS:
$n$ Specify an electronic time step duration of $n$/AIMD_TIME_STEP_CONVERSION a.u. If $n$ is less than the nuclear time step variable TIME_STEP, the electronic wave function will be integrated multiple times per nuclear time step, using a linear interpolation of nuclear quantities such as the energy gradient and derivative coupling. Note that $n$ must divide TIME_STEP evenly.
RECOMMENDATION:
Make AIMD_SHORT_TIME_STEP as large as possible while keeping the trace of the density matrix close to unity during long simulations. Note that while specifying an appropriate duration for the electronic time step is essential for maintaining accurate wave function time evolution, the electronic-only time steps employ linear interpolation to estimate important quantities. Consequently, a short electronic time step is not a substitute for a reasonable nuclear time step.

AIMD_STEPS

AIMD_STEPS
Specifies the requested number of molecular dynamics steps.
TYPE:
INTEGER
DEFAULT:
None.
OPTIONS:
User-specified.
RECOMMENDATION:
None.

AIMD_TEMP

AIMD_TEMP
Specifies a temperature (in Kelvin) for Maxwell-Boltzmann velocity sampling.
TYPE:
INTEGER
DEFAULT:
None
OPTIONS:
User-specified number of Kelvin.
RECOMMENDATION:
This variable is only useful in conjunction with AIMD_INIT_VELOC = THERMAL. Note that the simulations are run at constant energy, rather than constant temperature, so the mean nuclear kinetic energy will fluctuate in the course of the simulation.

AIMD_THERMOSTAT

AIMD_THERMOSTAT
Applies thermostatting to AIMD trajectories.
TYPE:
INTEGER
DEFAULT:
none
OPTIONS:
LANGEVIN Stochastic, white-noise Langevin thermostat NOSE_HOOVER Time-reversible, Nosé-Hoovery chain thermostat
RECOMMENDATION:
Use either thermostat for sampling the canonical (NVT) ensemble.

AIMD_TIME_STEP_CONVERSION

AIMD_TIME_STEP_CONVERSION
Modifies the molecular dynamics time step to increase granularity.
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
$n$ The molecular dynamics time step is TIME_STEP/$n$ a.u.
RECOMMENDATION:
None

AIRBED_ALPHA

AIRBED_ALPHA
Sets the value of $\alpha$.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
$n$ Corresponding to $\alpha$ = $n/1000$
RECOMMENDATION:
0 or -1200 for hBN surface

AIRBED

AIRBED
Perform an AIRBED calculation.
TYPE:
BOOLEAN
DEFAULT:
False
OPTIONS:
True Perform an AIRBED calculation. False Don’t perform an AIRBED calculation.
RECOMMENDATION:
Set the $rem variable DFT_D to EMPIRICAL_GRIMME. ANHAR_SEL ANHAR_SEL Select a subset of normal modes for subsequent anharmonic frequency analysis. TYPE: LOGICAL DEFAULT: FALSE Use all normal modes OPTIONS: TRUE Select subset of normal modes RECOMMENDATION: None ANHAR ANHAR Performing various nuclear vibrational theory (TOSH, VPT2, VCI) calculations to obtain vibrational anharmonic frequencies. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Carry out the anharmonic frequency calculation. FALSE Do harmonic frequency calculation. RECOMMENDATION: Since this calculation involves the third and fourth derivatives at the minimum of the potential energy surface, it is recommended that the GEOM_OPT_TOL_DISPLACEMENT, GEOM_OPT_TOL_GRADIENT and GEOM_OPT_TOL_ENERGY tolerances are set tighter. Note that VPT2 calculations may fail if the system involves accidental degenerate resonances. See the VCI$rem variable for more details about increasing the accuracy of anharmonic calculations.

ANTIBOND

ANTIBOND
Triggers Antibond subroutine to generate antibonding orbitals after a converged SCF
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Does not localize the virtual space. 1 Localizes the virtual space, one antibonding for every bond. 2,3 Fill the virtual space with antibonding orbitals-like guesses. 4 Does Frozen Natural Orbitals and leaves them on scratch for future jobs or visualization.
RECOMMENDATION:
None

ARI_R0

ARI_R0
Determines the value of the inner fitting radius (in Ångstroms)
TYPE:
INTEGER
DEFAULT:
4 A value of 4 Å will be added to the atomic van der Waals radius.
OPTIONS:
$n$ User defined radius.
RECOMMENDATION:
For some systems the default value may be too small and the calculation will become unstable.

ARI_R1

ARI_R1
Determines the value of the outer fitting radius (in Ångstroms)
TYPE:
INTEGER
DEFAULT:
5 A value of 5 Å will be added to the atomic van der Waals radius.
OPTIONS:
$n$ User defined radius.
RECOMMENDATION:
For some systems the default value may be too small and the calculation will become unstable. This value also determines, in part, the smoothness of the potential energy surface.

ARI

ARI
Toggles the use of the atomic resolution-of-the-identity (ARI) approximation.
TYPE:
LOGICAL
DEFAULT:
FALSE ARI will not be used by default for an RI-JK calculation.
OPTIONS:
TRUE Turn on ARI.
RECOMMENDATION:
For large (especially 1D and 2D) molecules the approximation may yield significant improvements in Fock evaluation time.

ASCI_CDETS

ASCI_CDETS
Specifies the number of determinants to search over during ASCI wavefunction growth steps.
TYPE:
INTEGER
DEFAULT:
-5
OPTIONS:
$N>0$ search from the top $N$ determinants $N<0$ search from the top determinants whose cumulative weight in the wavefunction corresponds to $1-2^{N}$
RECOMMENDATION:
Using a dynamically determined value ($N<0$) gives better results.

ASCI_DAVIDSON_GUESS

ASCI_DAVIDSON_GUESS
Specifies the truncated CI guess used for ASCI’s Davidson solver.
TYPE:
INTEGER
DEFAULT:
2
OPTIONS:
$N$ Order of the truncated CI to solve explicitly ASCI Davidson guess.
RECOMMENDATION:
Accurate excited states and rapid convergence of the ground state benefit from a good zero-order guess for the low energy spectrum. The default is often sufficient.

ASCI_DIAG

ASCI_DIAG
Specifies the diagonalization procedure.
TYPE:
INTEGER
DEFAULT:
2
OPTIONS:
1 Davidson solver 2 Eigen sparse matrix solver
RECOMMENDATION:
Use 2 for best trade-off of speed and memory usage. If memory usage becomes to great, switch to 1.

ASCI_NDETS

ASCI_NDETS
Specifies the number of determinants to include in the ASCI wavefunction.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
$N$ for a wavefunction with $N$ determinants
RECOMMENDATION:
Typical ASCI expansions range from 50,000 to 2,000,000 determinants depending on active space size, complexity of problem, and desired accuracy

ASCI_RESTART

ASCI_RESTART
Specifies whether to initialize the ASCI wavefunction with the wf_data file.
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
TRUE read CI coefficients from the wf_data file FALSE do not read the CI coefficients from disk
RECOMMENDATION:

ASCI_SKIP_PT2

ASCI_SKIP_PT2
Specifies whether ASCI PT2 correction should be calculated.
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
FALSE compute ASCI PT2 contribution TRUE do not compute ASCI PT2 contribution
RECOMMENDATION:
The PT2 correction is essential to obtaining converged ASCI energies.

ASCI_SPIN_PURIFY

ASCI_SPIN_PURIFY
Indicates whether or not the ASCI wavefunction should be augmented with missing determinants to ensure a spin-pure state.
TYPE:
BOOLEAN
DEFAULT:
FALSE
OPTIONS:
TRUE augment the wavefunction with determinants to ensure a spin eigenstate FALSE do not augment the wavefunction
RECOMMENDATION:

ASCI_USE_NAT_ORBS

ASCI_USE_NAT_ORBS
Specifies whether rotation to a natural orbital basis should be carried out between growth steps.
TYPE:
BOOLEAN
DEFAULT:
TRUE
OPTIONS:
TRUE rotate to a natural orbital basis between growth wavefunction growth steps FALSE do not rotate to a natural orbital basis
RECOMMENDATION:
Natural orbital rotations significantly improve the compactness and therefore accuracy of the ASCI wavefunction.

AUX_BASIS_CORR

AUX_BASIS_CORR
Sets the auxiliary basis set for RI-MP2 to be used or invokes RI-MP2 in case of double-hybrid DFT or MP2
TYPE:
STRING
DEFAULT:
No default auxiliary basis set
OPTIONS:
General, Gen User-defined. As for BASIS Symbol Use standard auxiliary basis sets as in the table below Mixed Use a combination of different basis sets
RECOMMENDATION:
Consult literature and Basis Set Exchange to aid your selection.

AUX_BASIS_J

AUX_BASIS_J
Sets the auxiliary basis set for RI-J to be used or invokes RI-J
TYPE:
STRING
DEFAULT:
No default auxiliary basis set
OPTIONS:
General, Gen User-defined. As for BASIS Symbol Use standard auxiliary basis sets as in the table below Mixed Use a combination of different basis sets
RECOMMENDATION:
Consult literature and Basis Set Exchange to aid your selection.

AUX_BASIS_K

AUX_BASIS_K
Sets the auxiliary basis set for RI-K or occ-RI-K to be used or invokes occ-RI-K
TYPE:
STRING
DEFAULT:
No default auxiliary basis set
OPTIONS:
General, Gen User-defined. As for BASIS Symbol Use standard auxiliary basis sets as in the table below Mixed Use a combination of different basis sets
RECOMMENDATION:
Consult literature and Basis Set Exchange to aid your selection.

AUX_BASIS

AUX_BASIS
Sets the auxiliary basis set to be used
TYPE:
STRING
DEFAULT:
No default auxiliary basis set
OPTIONS:
General, Gen User-defined. As for BASIS Symbol Use standard auxiliary basis sets as in the table below Mixed Use a combination of different basis sets
RECOMMENDATION:
Consult literature and Basis Set Exchange to aid your selection.

BASIS2

BASIS2
Defines the (small) second basis set.
TYPE:
STRING
DEFAULT:
No default for the second basis set.
OPTIONS:
Symbol Use standard basis sets as for BASIS. BASIS2_GEN General BASIS2 BASIS2_MIXED Mixed BASIS2
RECOMMENDATION:
BASIS2 should be smaller than BASIS. There is little advantage to using a basis larger than a minimal basis when BASIS2 is used for initial guess purposes. Larger, standardized BASIS2 options are available for dual-basis calculations as discussed in Section 4.7 and summarized in Table 4.2.

BASISPROJTYPE

BASISPROJTYPE
Determines which method to use when projecting the density matrix of BASIS2
TYPE:
STRING
DEFAULT:
FOPPROJECTION (when DUAL_BASIS_ENERGY=false) OVPROJECTION (when DUAL_BASIS_ENERGY=true)
OPTIONS:
FOPPROJECTION Construct the Fock matrix in the second basis OVPROJECTION Projects MOs from BASIS2 to BASIS.
RECOMMENDATION:
None

BASIS_LIN_DEP_THRESH

BASIS_LIN_DEP_THRESH
Sets the threshold for determining linear dependence in the basis set
TYPE:
INTEGER
DEFAULT:
6 Corresponding to a threshold of $10^{-6}$
OPTIONS:
$n$ Sets the threshold to $10^{-n}$
RECOMMENDATION:
Set to 5 or smaller if you have a poorly behaved SCF and you suspect linear dependence in you basis set. Lower values (larger thresholds) may affect the accuracy of the calculation.

BASIS

BASIS
Sets the basis set to be used
TYPE:
STRING
DEFAULT:
No default basis set
OPTIONS:
General, Gen User-defined. See section below Symbol Use standard basis sets as in the table below Mixed Use a combination of different basis sets
RECOMMENDATION:
Consult literature and reviews to aid your selection.

BECKE_SHIFT

BECKE_SHIFT
Controls atomic cell shifting in determination of Becke weights.
TYPE:
STRING
DEFAULT:
BRAGG_SLATER
OPTIONS:
UNSHIFTED Use Becke weighting without atomic size corrections, based on bond midpoints. BRAGG_SLATER Use the empirical radii introduced by Bragg and Slater. UNIVERSAL_DENSITY Use the ab initio radii introduced by Pacios.
RECOMMENDATION:
If interested in the partitioning of the default atomic quadrature, use UNSHIFTED. If using for physical interpretation, choose BRAGG_SLATER or UNIVERSAL_DENSITY. All cDFT calculations and calculations where POP_BECKE = TRUE will default to BRAGG_SLATER radii, otherwise the default grid is UNSHIFTED.

BONDED_EDA

BONDED_EDA
Use the bonded ALMO-EDA.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not perform bonded ALMO-EDA. 1 Perform ALMO-EDA with non-orthogonal CI. 2 Perform ALMO-EDA with spin-projected formalism.
RECOMMENDATION:
Set to 2 for all cases where the supersystem is closed shell, only use 1 for cases where the fragments have more than one unpaired spin each.

BOYSCALC

BOYSCALC
Specifies the Boys localized orbitals are to be calculated
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not perform localize the occupied space. 1 Allow core-valence mixing in Boys localization. 2 Localize core and valence separately.
RECOMMENDATION:
None

BOYS_CIS_NUMSTATE

BOYS_CIS_NUMSTATE
Define how many states to mix with Boys localized diabatization. These states must be specified in the $localized_diabatization section. TYPE: INTEGER DEFAULT: 0 Do not perform Boys localized diabatization. OPTIONS: 2 to N where N is the number of CIS states requested (CIS_N_ROOTS) RECOMMENDATION: It is usually not wise to mix adiabatic states that are separated by more than a few eV or a typical reorganization energy in solvent. CAGE_CHARGE CAGE_CHARGE Defines the total charge of the cage. TYPE: INTEGER DEFAULT: 400 Add a cage charged +4e. OPTIONS: $n$ Total charge of the cage is $n/100$ a.u. RECOMMENDATION: None CAGE_POINTS CAGE_POINTS Defines number of point charges for the spherical cage. TYPE: INTEGER DEFAULT: 100 OPTIONS: $n$ Number of point charges to use. RECOMMENDATION: None CAGE_RADIUS CAGE_RADIUS Defines radius of the charged cage. TYPE: INTEGER DEFAULT: 225 OPTIONS: $n$ radius is $n/100$ Å. RECOMMENDATION: None CALC_NAC CALC_NAC Whether or not nonadiabatic couplings will be calculated for the EOM-CC, CIS, and TDDFT wave functions. TYPE: INTEGER DEFAULT: 0 (do not compute NAC) OPTIONS: 1 NYI for EOM-CC 2 Compute NACs using Szalay’s approach (this what needs to be specified for EOM-CC). RECOMMENDATION: Additional response equations will be solved and gradients for all EOM states and for summed states will be computed, which increases the cost of calculations. Request only when needed and do not ask for too many EOM states. CALC_SOC CALC_SOC Whether or not the spin-orbit couplings between CC/EOM/ADC/CIS/TDDFT electronic states will be calculated. In the CC/EOM-CC suite, by default the couplings are calculated between the CCSD reference and the EOM-CCSD target states. In order to calculate couplings between EOM states, CC_STATE_TO_OPT must specify the initial EOM state. If NTO analysis is requested, analysis of spinless transition density matrices will be performed and the spin–orbit integrals over NTO pairs will be printed. TYPE: INTEGER/LOGICAL DEFAULT: FALSE (no spin-orbit couplings will be calculated) OPTIONS: 0/FALSE (no spin-orbit couplings will be calculated) 1/TRUE Activates SOC calculation. EOM-CC/EOM-MP2 only: spin-orbit couplings will be computed with the new code with L+/L- averaging 2 EOM-CC/EOM-MP2 only: spin-orbit couplings will be computed with the new code without L+/L- averaging 3 EOM-CC/EOM-MP2 only: spin-orbit couplings will be computed with the legacy code 4 One-electron spin-orbit couplings will be computed with effective nuclear charges (with L+/L- averaging for EOM-CC/MP2) RECOMMENDATION: CCMAN2 supports several variants of SOC calculation for EOM-CC/EOM-MP2 methods. One-electron and mean-field two-electron SOCs will be computed by default. To enable full two-electron SOCs, two-particle EOM properties must be turned on (see CC_EOM_PROP_TE). CALC_SOC CALC_SOC Controls whether to calculate the SOC constants for EOM-CC, RAS-CI, ADC, CIS, TDDFT/TDA and TDDFT/RPA. TYPE: INTEGER/LOGICAL DEFAULT: FALSE OPTIONS: FALSE Do not perform the SOC calculation. TRUE Perform the SOC calculation. RECOMMENDATION: Although TRUE/FALSE values will work, EOM-CC code has more variants of SOC evaluations. For details, consult with EOM section. CAP_X_END CAP_X_END Controls the upper onset limit for a series of CAP onsets, where the lower limit is given by CAP_X. The parameter value in a.u. is obtained by multiplying the given integer by $10^{-3}$. Currently only used in ADC methods. TYPE: INTEGER DEFAULT: CAP_X Do not compute a series of CAP onsets but only use a single CAP with an onset value of CAP_X. OPTIONS: $n>\text{\mbox{{\small CAP\_X}}}$ User-defined integer. RECOMMENDATION: Use this keyword if CAP onset series are desired. CAP_X_STEP CAP_X_STEP Controls the step size for a series of CAP onsets between CAP_X and CAP_X_END. The parameter value in a.u. is obtained by multiplying the given integer by $10^{-3}$. Currently only used in ADC methods. TYPE: INTEGER DEFAULT: 500 corresponding to 0.5 a.u. OPTIONS: $n>0$ User-defined integer. RECOMMENDATION: None. CAP_X CAP_X For ADC methods, in combination with a smoothed Voronoi-CAP (CAP_TYPE = 2) or a spherical CAP (CAP_TYPE = 0), this keyword controls the lower limit for a series of CAP onsets, where the upper limit is given by CAP_X_END. The parameter value in a.u. is obtained by multiplying the given integer by $10^{-3}$. In this case, the onset value defines the region around the molecule with zero CAP strength. In combination with a cuboid CAP (CAP_TYPE = 1) or in general for other electronic structure methods (see 7.10.9 for further details), this keyword controls the CAP onset in $x$ direction. TYPE: INTEGER DEFAULT: 0 OPTIONS: $n>0$ User-defined integer. RECOMMENDATION: Usually, values of 2000 to 4000 (corresponding to onset values between 2.0 and 4.0 a.u.) give reasonable results. CAS_DAVIDSON_MAXVECTORS CAS_DAVIDSON_MAXVECTORS Specifies the maximum number of vectors to augment the Davidson search space in CAS. TYPE: INTEGER DEFAULT: 10 OPTIONS: $N$ sets the maximum Davidson subspace size to $N$+CAS_N_ROOTS RECOMMENDATION: The default should be suitable in most cases CAS_DAVIDSON_TOL CAS_DAVIDSON_TOL Specifies the tolerance for the Davidson solver used in CAS. TYPE: INTEGER DEFAULT: 5 OPTIONS: $N$ for a threshold of $10^{-N}$ RECOMMENDATION: The default should be suitable in most cases CAS_DO_1X CAS_DO_1X Do perturbative hole (h) and particle (p) correction? TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Do perturbative hole (h) and particle (p) correction FALSE Do not do perturbative hole (h) and particle (p) correction RECOMMENDATION: None. CAS_DO_2x CAS_DO_2x Do perturbative 2x (h,p,hp,hh,pp) correction? TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Do perturbative 2x correction FALSE Do not do perturbative 2x correction RECOMMENDATION: None. CAS_DO_3x CAS_DO_3x Do perturbative 3x (h,p,hp,hh,pp,hhp,hpp) correction? TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Do perturbative 3x correction FALSE Do not do perturbative 3x correction RECOMMENDATION: None. CAS_DO_DOUBLES CAS_DO_DOUBLES Do perturbative (h,p,hp,hh,pp,hhp,hpp) correction + MP2 RAS1->RAS3 doubles? TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Do perturbative (h,p,hp,hh,pp,hhp,hpp) + MP2 RAS1->RAS3 doubles correction FALSE Do not do the correction RECOMMENDATION: None. CAS_DO_NDPT CAS_DO_NDPT Do non-degenerate perturbation theory? TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Do non-degenerate perturbation theory. FALSE Do not use non-degenerate perturbation theory. RECOMMENDATION: None. CAS_DO_SINGLES CAS_DO_SINGLES Do perturbative singles (h,p,hp) correction? TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Do perturbative singles correction FALSE Do not do perturbative singles correction RECOMMENDATION: None. CAS_LEVEL_SHIFT CAS_LEVEL_SHIFT Use a denominator level-shift? TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Use the denominator level-shift FALSE Do not use the denominator level-shift RECOMMENDATION: None. CAS_LOCAL_ALGO CAS_LOCAL_ALGO Passed into localizer. Set to 1 if doing Boys localization. TYPE: INTEGER DEFAULT: 0 OPTIONS: $0$ No localization $1$ Boys localization $2$ Pipek-Mezey localization RECOMMENDATION: None. CAS_LOCAL CAS_LOCAL Determines whether to do localization. TYPE: INTEGER DEFAULT: 0 OPTIONS: $0$ No localization $1$ Boys localization $2$ Pipek-Mezey localization RECOMMENDATION: None. CAS_METHOD CAS_METHOD Indicates whether orbital optimization is requested. TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Not running a CAS calculation 1 CAS-CI (no orbital optimization) 2 CASSCF (orbital optimization) RECOMMENDATION: Use 2 for best accuracy, but such computations may become infeasible for large active spaces. CAS_M_S CAS_M_S The number of unpaired electrons desired in the CAS wavefunction. TYPE: INTEGER DEFAULT: 0 OPTIONS: $N$ for a wavefunction with $N$ unpaired electrons RECOMMENDATION: CAS_N_ELEC CAS_N_ELEC Specifies the number of active electrons. TYPE: INTEGER DEFAULT: 0 OPTIONS: $N$ include $N$ electrons in the active space -1 include all electrons in the active space RECOMMENDATION: Use the smallest active space possible for the given system. CAS_N_ORB CAS_N_ORB Specifies the number of active orbitals. TYPE: INTEGER DEFAULT: 0 OPTIONS: $N$ include $N$ orbitals in the active space -1 include all orbitals in the active space RECOMMENDATION: Use the smallest active space possible for the given system. CAS_N_ROOTS CAS_N_ROOTS Specifies the number of electronic states to determine. TYPE: INTEGER DEFAULT: 1 OPTIONS: $N$ solve for $N$ roots of the Hamiltonian RECOMMENDATION: CAS_QDPT_ORDER CAS_QDPT_ORDER Order of terms kept in the quasi-degenerate perturbation theory denominator expansion. TYPE: INTEGER DEFAULT: None. OPTIONS: $n$ Keep terms of order $n$ in the denominator expansion. RECOMMENDATION: None. CAS_SAVE_NAT_ORBS CAS_SAVE_NAT_ORBS Save the CAS natural orbitals in place of the reference orbitals. TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: TRUE overwrite the reference orbitals with CAS natural orbitals FALSE do not save the CAS natural orbitals RECOMMENDATION: CAS_SOLVER CAS_SOLVER Specifies the solver to be used for the active space. TYPE: INTEGER DEFAULT: 1 OPTIONS: 1 CAS-CI/CASSCF 2 ASCI (see Section 6.21) 3 Truncated CI (CIS, CISD, CISDT, etc.) RECOMMENDATION: CAS_SPARSE CAS_SPARSE Use a sparse matrix multiply when forming the effective Hamiltonian? TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Use sparse matrix multiply in forming effective Hamiltonian FALSE Do not use sparse matrix multiply in forming effective Hamiltonian RECOMMENDATION: None. Can be useful for larger numbers of spin-flips. CAS_THRESH CAS_THRESH Specifies the threshold for matrix elements to be included in the CAS Hamiltonian. TYPE: INTEGER DEFAULT: 12 OPTIONS: $N$ for a threshold of $10^{-N}$ RECOMMENDATION: CAS_USE_RI CAS_USE_RI Indicates whether the resolution of the identity approximation should be used. TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: FALSE Compute 2-electron integrals analytically TRUE Use the RI approximation for 2-electron integrals RECOMMENDATION: Analytic integrals are more accurate, RI integrals are faster CCVB_GUESS CCVB_GUESS Specifies the initial guess for CCVB calculations TYPE: INTEGER DEFAULT: NONE OPTIONS: 1 Standard GVBMAN guess (orbital localization via GVB_LOCAL + Sano procedure). 2 Use orbitals from previous GVBMAN calculation, along with SCF_GUESS = READ. 3 Convert UHF orbitals into pairing VB form. RECOMMENDATION: Option 1 is the most useful overall. The success of GVBMAN methods is often dependent on localized orbitals, and this guess shoots for these. Option 2 is useful for comparing results to other GVBMAN methods, or if other GVBMAN methods are able to obtain a desired result more efficiently. Option 3 can be useful for bond-breaking situations when a pertinent UHF solution has been found. It works best for small systems, or if the unrestriction is a local phenomenon within a larger molecule. If the unrestriction is non-local and the system is large, this guess will often produce a solution that is not the global minimum. Any UHF solution has a certain number of pairs that are unrestricted, and this will be output by the program. If GVB_N_PAIRS exceeds this number, the standard GVBMAN initial-guess procedure will be used to obtain a guess for the excess pairs CCVB_METHOD CCVB_METHOD Optionally modifies the basic CCVB method TYPE: INTEGER DEFAULT: 1 OPTIONS: 1 Standard CCVB model 3 Independent electron pair approximation (IEPA) to CCVB 4 Variational PP (the CCVB reference energy) RECOMMENDATION: Option 1 is generally recommended. Option 4 is useful for preconditioning, and for obtaining localized-orbital solutions, which may be used in subsequent calculations. It is also useful for cases in which the regular GVBMAN PP code becomes variationally unstable. Option 3 is a simple independent-amplitude approximation to CCVB. It avoids the cubic-scaling amplitude equations of CCVB, and also is able to reach the correct dissociation energy for any molecular system (unlike regular CCVB which does so only for cases in which UHF can reach a correct dissociate limit). However the IEPA approximation to CCVB is sometimes variationally unstable, which we have yet to observe in regular CCVB. CC_1HPOL CC_1HPOL Specifies the approach for calculating the first hyperpolarizability of the CCSD wave function. TYPE: INTEGER DEFAULT: 0 (CCSD first hyperpolarizability will not be calculated) OPTIONS: 1 (damped-response expectation-value approach with only first-order response wave functions) 3 (damped-response expectation-value approach with second-order response density matrices for wave-function and natural orbital analyses) RECOMMENDATION: CCSD first hyperpolarizabilities are expensive since they require solving a huge number of first- and second-order response equations. Do no request this property unless you need it. CC_BACKEND CC_BACKEND Used to specify the computational back-end of CCMAN2. TYPE: STRING DEFAULT: VM Default shared-memory disk-based back-end OPTIONS: XM libxm shared-memory disk-based back-end INCORE in-core memory back-end RECOMMENDATION: Use XM for large jobs with limited memory or when the performance of the default disk-based back-end is not satisfactory, INCORE for small jobs that fit in main memory. CC_CANONIZE_FINAL CC_CANONIZE_FINAL Whether to semi-canonicalize orbitals at the end of the ground state calculation. TYPE: LOGICAL DEFAULT: FALSE unless required OPTIONS: TRUE/FALSE RECOMMENDATION: Should not normally have to be altered. CC_CANONIZE_FREQ CC_CANONIZE_FREQ The orbitals will be semi-canonicalized every $n$ theta resets. The thetas (orbital rotation angles) are reset every CC_RESET_THETA iterations. The counting of iterations differs for active space (VOD, VQCCD) calculations, where the orbitals are always canonicalized at the first theta-reset. TYPE: INTEGER DEFAULT: 50 OPTIONS: $n$ User-defined integer RECOMMENDATION: Smaller values can be tried in cases that do not converge. CC_CANONIZE CC_CANONIZE Whether to semi-canonicalize orbitals at the start of the calculation (i.e. Fock matrix is diagonalized in each orbital subspace) TYPE: LOGICAL DEFAULT: TRUE OPTIONS: TRUE/FALSE RECOMMENDATION: Should not normally have to be altered. CC_CONVERGENCE CC_CONVERGENCE Overall convergence criterion for the coupled-cluster codes. This is designed to ensure at least $n$ significant digits in the calculated energy, and automatically sets the other convergence-related variables (CC_E_CONV, CC_T_CONV, CC_THETA_CONV, CC_THETA_GRAD_CONV) [$10^{-n}$]. TYPE: INTEGER DEFAULT: 6 Energies. 7 Gradients. OPTIONS: $n$ Corresponding to $10^{-n}$ convergence criterion. Amplitude convergence is set automatically to match energy convergence. RECOMMENDATION: Use the default CC_DIIS12_SWITCH CC_DIIS12_SWITCH When to switch from DIIS2 to DIIS1 procedure, or when DIIS2 procedure is required to generate DIIS guesses less frequently. Total value of DIIS error vector must be less than $10^{-n}$, where $n$ is the value of this option. TYPE: INTEGER DEFAULT: 5 OPTIONS: $n$ User-defined integer RECOMMENDATION: None CC_DIIS_FREQ CC_DIIS_FREQ DIIS extrapolation will be attempted every n iterations. However, DIIS2 will be attempted every iteration while total error vector exceeds CC_DIIS12_SWITCH. DIIS1 cannot generate guesses more frequently than every 2 iterations. TYPE: INTEGER DEFAULT: 2 OPTIONS: $N$ User-defined integer RECOMMENDATION: None CC_DIIS_MAX_OVERLAP CC_DIIS_MAX_OVERLAP DIIS extrapolations will not begin until square root of the maximum element of the error overlap matrix drops below this value. TYPE: DOUBLE DEFAULT: 100 Corresponding to 1.0 OPTIONS: $abcde$ Integer code is mapped to $abc\times 10^{-de}$ RECOMMENDATION: None CC_DIIS_MIN_OVERLAP CC_DIIS_MIN_OVERLAP The DIIS procedure will be halted when the square root of smallest element of the error overlap matrix is less than $10^{-n}$, where $n$ is the value of this option. Small values of the B matrix mean it will become near-singular, making the DIIS equations difficult to solve. TYPE: INTEGER DEFAULT: 11 OPTIONS: $n$ User-defined integer RECOMMENDATION: None CC_DIIS_SIZE CC_DIIS_SIZE Specifies the maximum size of the DIIS space. TYPE: INTEGER DEFAULT: 7 OPTIONS: $n$ User-defined integer RECOMMENDATION: Larger values involve larger amounts of disk storage. CC_DIIS_START CC_DIIS_START Iteration number when DIIS is turned on. Set to a large number to disable DIIS. TYPE: INTEGER DEFAULT: 3 OPTIONS: $n$ User-defined RECOMMENDATION: Occasionally DIIS can cause optimized orbital coupled-cluster calculations to diverge through large orbital changes. If this is seen, DIIS should be disabled. CC_DIIS CC_DIIS Specify the version of Pulay’s Direct Inversion of the Iterative Subspace (DIIS) convergence accelerator to be used in the coupled-cluster code. TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Activates procedure 2 initially, and procedure 1 when gradients are smaller than DIIS12_SWITCH. 1 Uses error vectors defined as differences between parameter vectors from successive iterations. Most efficient near convergence. 2 Error vectors are defined as gradients scaled by square root of the approximate diagonal Hessian. Most efficient far from convergence. RECOMMENDATION: DIIS1 can be more stable. If DIIS problems are encountered in the early stages of a calculation (when gradients are large) try DIIS1. CC_DIRECT_RI CC_DIRECT_RI Controls use of RI and Cholesky integrals in conventional (undecomposed) form TYPE: LOGICAL DEFAULT: FALSE OPTIONS: FALSE use all integrals in decomposed format TRUE transform all RI or Cholesky integral back to conventional format RECOMMENDATION: By default all integrals are used in decomposed format allowing significant reduction of memory use. If all integrals are transformed back (TRUE option) no memory reduction is achieved and decomposition error is introduced, however, the integral transformation is performed significantly faster and conventional CC/EOM algorithms are used. CC_DOV_THRESH CC_DOV_THRESH Specifies minimum allowed values for the coupled-cluster energy denominators. Smaller values are replaced by this constant during early iterations only, so the final results are unaffected, but initial convergence is improved when the HOMO-LUMO gap is small or when non-conventional references are used. TYPE: INTEGER DEFAULT: 0 OPTIONS: $abcde$ Integer code is mapped to $ab\times 10^{-de}$, e.g., $2501$ corresponds to 0.025, $99001$ corresponds to 0.99, etc. RECOMMENDATION: Increase to 0.25, 0.5 or 0.75 for non convergent coupled-cluster calculations. CC_DO_DYSON_EE CC_DO_DYSON_EE Whether excited-state or spin-flip state Dyson orbitals will be calculated for EOM-IP/EA-CCSD calculations with CCMAN. TYPE: LOGICAL DEFAULT: FALSE (the option must be specified to run this calculation) OPTIONS: TRUE/FALSE RECOMMENDATION: none CC_DO_DYSON CC_DO_DYSON CCMAN2: starts all types of Dyson orbitals calculations. Desired type is determined by requesting corresponding EOM-XX transitions CCMAN: whether the reference-state Dyson orbitals will be calculated for EOM-IP/EA-CCSD calculations. TYPE: LOGICAL DEFAULT: FALSE (the option must be specified to run this calculation) OPTIONS: TRUE/FALSE RECOMMENDATION: none CC_DO_FESHBACH CC_DO_FESHBACH Activates calculation of resonance widths using Feshbach-Fano approach. TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 do not invoke Feshbach-Fano calculation 1 invoke Feshbach-Fano calculation of the resonance width 2 invoke Feshbach-Fano calculation of the resonance width and resonance shift RECOMMENDATION: Initial and final states should be correctly specified. CC_EOM_2PA CC_EOM_2PA Whether or not the transition moments and cross-sections for two-photon absorption will be calculated. By default, the transition moments are calculated between the CCSD reference and the EOM-CCSD target states. In order to calculate transition moments between a set of EOM-CCSD states and another EOM-CCSD state, the CC_STATE_TO_OPT must be specified for this state. If 2PA NTO analysis is requested, the CC_EOM_2PA value is redundant as long as CC_EOM_2PA $>0$. TYPE: INTEGER DEFAULT: 0 (do not compute 2PA transition moments) OPTIONS: 1 Compute 2PA using the fastest algorithm (use $\tilde{\sigma}$-intermediates for canonical and $\sigma$-intermediates for RI/CD response calculations). 2 Use $\sigma$-intermediates for 2PA response equation calculations. 3 Use $\tilde{\sigma}$-intermediates for 2PA response equation calculations. RECOMMENDATION: Additional response equations (6 for each target state) will be solved, which increases the cost of calculations. The cost of 2PA moments is about 10 times that of energy calculation. Use the default algorithm. Setting CC_EOM_2PA $>0$ turns on CC_TRANS_PROP. CC_EOM_PROP_TE CC_EOM_PROP_TE Request for calculation of non-relaxed two-particle EOM-CC properties. The two-particle properties currently include $\langle S^{2}\rangle$. The one-particle properties also will be calculated, since the additional cost of the one-particle properties calculation is inferior compared to the cost of $\langle S^{2}\rangle$. The variable CC_EOM_PROP must be also set to TRUE. Alternatively, CC_CALC_SSQ can be used to request $\langle S^{2}\rangle$ calculation. TYPE: LOGICAL DEFAULT: FALSE (no two-particle properties will be calculated) OPTIONS: FALSE, TRUE RECOMMENDATION: The two-particle properties are computationally expensive since they require calculation and use of the two-particle density matrix (the cost is approximately the same as the cost of an analytic gradient calculation). Do not request the two-particle properties unless you really need them. CC_EOM_PROP CC_EOM_PROP Whether or not the non-relaxed (expectation value) one-particle EOM-CCSD target state properties will be calculated. The properties currently include permanent dipole moment, angular momentum projections, the second moments $\langle X^{2}\rangle$, $\langle Y^{2}\rangle$, and $\langle Z^{2}\rangle$ of electron density, and the total $\langle R^{2}\rangle=\langle X^{2}\rangle+\langle Y^{2}\rangle+\langle Z^{2}\rangle$ (in atomic units). Incompatible with JOBTYPE = FORCE, OPT, FREQ. TYPE: LOGICAL DEFAULT: FALSE (no one-particle properties will be calculated) OPTIONS: FALSE, TRUE RECOMMENDATION: Additional equations (EOM-CCSD equations for the left eigenvectors) need to be solved for properties, approximately doubling the cost of calculation for each irrep. The cost of the one-particle properties calculation itself is low. The one-particle density of an EOM-CCSD target state can be analyzed with NBO or libwfa packages by specifying the state with CC_STATE_TO_OPT and requesting NBO = TRUE and CC_EOM_PROP = TRUE. CC_EOM_RIXS CC_EOM_RIXS Whether or not the RIXS scattering moments and cross-sections will be calculated. TYPE: INTEGER DEFAULT: 0 do not compute RIXS cross-sections OPTIONS: 1 Perform RIXS within fc-CVS-EOM-EE-CCSD using the response wave functions of the CCSD reference state only 2 Perform RIXS within fc-CVS-EOM-EE-CCSD response theory along with the wave-function analysis of RIXS transition density matrices 11 Perform RIXS within the standard EOM-EE-CCSD using the response wave functions of the CCSD reference state only 12 Use $\sigma$-intermediates for RIXS response calculations within the standard EOM-EE-CCSD RECOMMENDATION: Use 1 to deploy fc-CVS-EOM-EE-CCSD with robust convergence CC_ERASE_DP_INTEGRALS CC_ERASE_DP_INTEGRALS Controls storage of requisite objects computed with double precision in a single-precision calculation TYPE: INTEGER DEFAULT: 0 store OPTIONS: 1 do not store RECOMMENDATION: Do not erase integrals if clean-up in double precision is intended. CC_E_CONV CC_E_CONV Convergence desired on the change in total energy, between iterations. TYPE: INTEGER DEFAULT: 10 OPTIONS: $n$ $10^{-n}$ convergence criterion. RECOMMENDATION: None CC_FESHBACH_CW CC_FESHBACH_CW Activates Coulomb wave description of the ejected electron. TYPE: INTEGER DEFAULT: 0 OPTIONS: 0 Use plane wave 1 Use Coulomb wave RECOMMENDATION: Additional details need to be specified in$coulomb_wave section.

CC_FESHBACH_DELTA_INTB

CC_FESHBACH_DELTA_INTB
Specifies integration limits in calculation of energy shift in Feshbach-Fano calculations.
TYPE:
INTEGER
DEFAULT:
Preset
OPTIONS:
$n$ corresponds to energy limit in eV
RECOMMENDATION:
Use default.

CC_FESHBACH_DELTA_INTC

CC_FESHBACH_DELTA_INTC
Specifies integration limits in calculation of energy shift in Feshbach-Fano calculations.
TYPE:
INTEGER
DEFAULT:
Preset
OPTIONS:
$n$ corresponds to energy limit in eV
RECOMMENDATION:
Use default.

CC_FNO_THRESH

CC_FNO_THRESH
Initialize the FNO truncation and sets the threshold to be used for both cutoffs (OCCT and POVO)
TYPE:
INTEGER
DEFAULT:
None
OPTIONS:
range 0000-10000 $abcd$ Corresponding to $ab.cd$%
RECOMMENDATION:
None

CC_FNO_USEPOP

CC_FNO_USEPOP
Selection of the truncation scheme
TYPE:
INTEGER
DEFAULT:
1 OCCT
OPTIONS:
0 POVO
RECOMMENDATION:
None

CC_FULLRESPONSE

CC_FULLRESPONSE
Fully relaxed properties (including orbital relaxation terms) will be computed. The variable CC_REF_PROP must be also set to TRUE.
TYPE:
LOGICAL
DEFAULT:
FALSE (no orbital response will be calculated)
OPTIONS:
FALSE, TRUE
RECOMMENDATION:
Not available for non UHF/RHF references and for the methods that do not have analytic gradients (e.g., QCISD).

CC_HESS_THRESH

CC_HESS_THRESH
Minimum allowed value for the orbital Hessian. Smaller values are replaced by this constant.
TYPE:
DOUBLE
DEFAULT:
102 Corresponding to 0.01
OPTIONS:
$abcde$ Integer code is mapped to $abc\times 10^{-de}$
RECOMMENDATION:
None

CC_INCL_CORE_CORR

CC_INCL_CORE_CORR
Whether to include the correlation contribution from frozen core orbitals in non iterative (2) corrections, such as OD(2) and CCSD(2).
TYPE:
LOGICAL
DEFAULT:
TRUE
OPTIONS:
TRUE FALSE
RECOMMENDATION:
Use the default unless no core-valence or core correlation is desired (e.g., for comparison with other methods or because the basis used cannot describe core correlation).

CC_ITERATE_ON

CC_ITERATE_ON
In active space calculations, use a “mixed” iteration procedure if the value is greater than 0. Then if the RMS orbital gradient is larger than the value of CC_THETA_GRAD_THRESH, micro-iterations will be performed to converge the occupied-virtual mixing angles for the current active space. The maximum number of space iterations is given by this option.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
$n$ Up to $n$ occupied-virtual iterations per overall cycle
RECOMMENDATION:
Can be useful for non-convergent active space calculations

CC_ITERATE_OV

CC_ITERATE_OV
In active space calculations, use a “mixed” iteration procedure if the value is greater than 0. Then, if the RMS orbital gradient is larger than the value of CC_THETA_GRAD_THRESH, micro-iterations will be performed to converge the occupied-virtual mixing angles for the current active space. The maximum number of such iterations is given by this option.
TYPE:
INTEGER
DEFAULT:
0 No “mixed” iterations
OPTIONS:
$n$ Up to $n$ occupied-virtual iterations per overall cycle
RECOMMENDATION:
Can be useful for non-convergent active space calculations.

CC_MAX_ITER

CC_MAX_ITER
Maximum number of iterations to optimize the coupled-cluster energy.
TYPE:
INTEGER
DEFAULT:
200
OPTIONS:
$n$ up to $n$ iterations to achieve convergence.
RECOMMENDATION:
None

CC_MEMORY

CC_MEMORY
Specifies the maximum size, in MB, of the buffers for in-core storage of block-tensors in CCMAN and CCMAN2.
TYPE:
INTEGER
DEFAULT:
50% of MEM_TOTAL. If MEM_TOTAL is not set, use 1.5 GB. A minimum of 192 MB is hard-coded.
OPTIONS:
$n$ Integer number of MB
RECOMMENDATION:
Larger values can give better I/O performance and are recommended for systems with large memory (add to your .qchemrc file. When running CCMAN2 exclusively on a node, CC_MEMORY should be set to 75–80% of the total available RAM. )

If CC_MP2NO_GUESS is TRUE, what kind of one-particle density matrix is used to make the guess orbitals?
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE 1 PDM from MP2 gradient theory. FALSE 1 PDM expanded to 2${}^{\mathrm{nd}}$ order in perturbation theory.
RECOMMENDATION:
The two definitions give generally similar performance.

CC_MP2NO_GUESS

CC_MP2NO_GUESS
Will guess orbitals be natural orbitals of the MP2 wave function? Alternatively, it is possible to use an effective one-particle density matrix to define the natural orbitals.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE Use natural orbitals from an MP2 one-particle density matrix (see CC_MP2NO_GRAD). FALSE Use current molecular orbitals from SCF.
RECOMMENDATION:
None

CC_ORBS_PER_BLOCK

CC_ORBS_PER_BLOCK
Specifies target (and maximum) size of blocks in orbital space.
TYPE:
INTEGER
DEFAULT:
16
OPTIONS:
$n$ Orbital block size of $n$ orbitals.
RECOMMENDATION:
None

CC_OSFNO

CC_OSFNO
Activation of OSFNO. Available only for open-shell references.
TYPE:
LOGICAL
DEFAULT:
FALSE do not activate
OPTIONS:
TRUE activate
RECOMMENDATION:
Use for EOM-SF-CCSD calculations from open-shell references. Available in CCMAN2 only.

CC_POL

CC_POL
Specifies the approach for calculating the polarizability of the CCSD wave function.
TYPE:
INTEGER
DEFAULT:
0 (CCSD polarizability will not be calculated)
OPTIONS:
1 (analytic-derivative or response-theory mixed symmetric-asymmetric approach) 2 (analytic-derivative or response-theory asymmetric approach) 3 (expectation-value approach with right response intermediates) 4 (expectation-value approach with left response intermediates) 13 (damped-response expectation-value approach with right response intermediates) 14 (damped-response expectation-value approach with left response intermediates) 15 (damped-response expectation-value approach with first-order response density matrices)
RECOMMENDATION:
CCSD polarizabilities are expensive since they require solving three/six (for static) or six/twelve (for dynamical) additional response equations. Do no request this property unless you need it.

CC_PRECONV_FZ

CC_PRECONV_FZ
In active space methods, whether to pre-converge other wave function variables for fixed initial guess of active space.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 No pre-iterations before active space optimization begins. $n$ Maximum number of pre-iterations via this procedure.
RECOMMENDATION:
None

CC_PRECONV_T2Z_EACH

CC_PRECONV_T2Z_EACH
Whether to pre-converge the cluster amplitudes before each change of the orbitals in optimized orbital coupled-cluster methods. The maximum number of iterations in this pre-convergence procedure is given by the value of this parameter.
TYPE:
INTEGER
DEFAULT:
0 (FALSE)
OPTIONS:
0 No pre-convergence before orbital optimization. $n$ Up to $n$ iterations in this pre-convergence procedure.
RECOMMENDATION:
A very slow last resort option for jobs that do not converge.

CC_PRECONV_T2Z

CC_PRECONV_T2Z
Whether to pre-converge the cluster amplitudes before beginning orbital optimization in optimized orbital cluster methods.
TYPE:
INTEGER
DEFAULT:
0 (FALSE) 10 If CC_RESTART, CC_RESTART_NO_SCF or CC_MP2NO_GUESS are TRUE
OPTIONS:
0 No pre-convergence before orbital optimization. $n$ Up to $n$ iterations in this pre-convergence procedure.
RECOMMENDATION:
Experiment with this option in cases of convergence failure.

CC_PRINT

CC_PRINT
Controls the output from post-MP2 coupled-cluster module of Q-Chem
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
$0-7$ higher values can lead to deforestation…
RECOMMENDATION:
Increase if you need more output and don’t like trees

CC_QCCD_THETA_SWITCH

CC_QCCD_THETA_SWITCH
QCCD calculations switch from OD to QCCD when the rotation gradient is below this threshold [$10^{-n}$]
TYPE:
INTEGER
DEFAULT:
2 $10^{-2}$ switchover
OPTIONS:
$n$ $10^{-n}$ switchover
RECOMMENDATION:
None

CC_REF_PROP_TE

CC_REF_PROP_TE
Request for calculation of non-relaxed two-particle CCSD properties. The two-particle properties currently include $\langle S^{2}\rangle$. The one-particle properties also will be calculated, since the additional cost of the one-particle properties calculation is inferior compared to the cost of $\langle S^{2}\rangle$. The variable CC_REF_PROP must be also set to TRUE.
TYPE:
LOGICAL
DEFAULT:
FALSE (no two-particle properties will be calculated)
OPTIONS:
FALSE, TRUE
RECOMMENDATION:
The two-particle properties are computationally expensive, since they require calculation and use of the two-particle density matrix (the cost is approximately the same as the cost of an analytic gradient calculation). Do not request the two-particle properties unless you really need them.

CC_REF_PROP

CC_REF_PROP
Whether or not the non-relaxed (expectation value) or full response (including orbital relaxation terms) one-particle CCSD properties will be calculated. The properties currently include permanent dipole moment, the second moments $\langle X^{2}\rangle$, $\langle Y^{2}\rangle$, and $\langle Z^{2}\rangle$ of electron density, and the total $\langle R^{2}\rangle=\langle X^{2}\rangle+\langle Y^{2}\rangle+\langle Z^{2}\rangle$ (in atomic units). Incompatible with JOBTYPE = FORCE, OPT, or FREQ.
TYPE:
LOGICAL
DEFAULT:
FALSE (no one-particle properties will be calculated)
OPTIONS:
FALSE, TRUE
RECOMMENDATION:
Additional equations need to be solved (lambda CCSD equations) for properties with the cost approximately the same as CCSD equations. Use the default if you do not need properties. The cost of the properties calculation itself is low. The CCSD one-particle density can be analyzed with NBO package by specifying NBO = TRUE, CC_REF_PROP = TRUE, and i JOBTYPE = FORCE.

CC_RESET_THETA

CC_RESET_THETA
The reference MO coefficient matrix is reset every n iterations to help overcome problems associated with the theta metric as theta becomes large.
TYPE:
INTEGER
DEFAULT:
15
OPTIONS:
$n$ $n$ iterations between resetting orbital rotations to zero.
RECOMMENDATION:
None

CC_RESTART_NO_SCF

CC_RESTART_NO_SCF
Should an optimized orbital coupled cluster calculation begin with optimized orbitals from a previous calculation? When TRUE, molecular orbitals are initially orthogonalized, and CC_PRECONV_T2Z and CC_CANONIZE are set to TRUE while other guess options are set to FALSE
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE/FALSE
RECOMMENDATION:
None

CC_RESTART

CC_RESTART
Allows an optimized orbital coupled cluster calculation to begin with an initial guess for the orbital transformation matrix U other than the unit vector. The scratch file from a previous run must be available for the U matrix to be read successfully.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE Use unit initial guess. TRUE Activates CC_PRECONV_T2Z, CC_CANONIZE, and turns off CC_MP2NO_GUESS
RECOMMENDATION:
Useful for restarting a job that did not converge, if files were saved.

CC_RESTR_AMPL

CC_RESTR_AMPL
Controls the restriction on amplitudes is there are restricted orbitals
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
0 All amplitudes are in the full space 1 Amplitudes are restricted, if there are restricted orbitals
RECOMMENDATION:
None

CC_RESTR_TRIPLES

CC_RESTR_TRIPLES
Controls which space the triples correction is computed in
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Triples are computed in the full space 1 Triples are restricted to the active space
RECOMMENDATION:
None

CC_REST_AMPL

CC_REST_AMPL
Forces the integrals, $T$, and $R$ amplitudes to be determined in the full space even though the CC_REST_OCC and CC_REST_VIR keywords are used.
TYPE:
LOGICAL
DEFAULT:
TRUE
OPTIONS:
FALSE Do apply restrictions TRUE Do not apply restrictions
RECOMMENDATION:
None

CC_REST_OCC

CC_REST_OCC
Sets the number of restricted occupied orbitals including active core occupied orbitals.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
$n$ Restrict $n$ energetically lowest occupied orbitals to correspond to the active core space.
RECOMMENDATION:
Example: cytosine with the molecular formula C${}_{4}$H${}_{5}$N${}_{3}$O includes one oxygen atom. To calculate O 1s core-excited states, $n$ has to be set to 1, because the 1s orbital of oxygen is the energetically lowest. To obtain the N 1s core excitations, the integer $n$ has to be set to 4, because the 1s orbital of the oxygen atom is included as well, since it is energetically below the three 1s orbitals of the nitrogen atoms. Accordingly, to simulate the C 1s spectrum of cytosine, $n$ must be set to 8.

CC_REST_TRIPLES

CC_REST_TRIPLES
Restricts $R_{3}$ amplitudes to the active space, i.e., one electron should be removed from the active occupied orbital and one electron should be added to the active virtual orbital.
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
1 Applies the restrictions
RECOMMENDATION:
None

CC_REST_VIR

CC_REST_VIR
Sets the number of restricted virtual orbitals including frozen virtual orbitals.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
$n$ Restrict $n$ virtual orbitals.
RECOMMENDATION:
None

CC_SCALE_AMP

CC_SCALE_AMP
If not 0, scales down the step for updating coupled-cluster amplitudes in cases of problematic convergence.
TYPE:
INTEGER
DEFAULT:
0 no scaling
OPTIONS:
$abcd$ Integer code is mapped to $abcd\times 10^{-2}$, e.g., $90$ corresponds to 0.9
RECOMMENDATION:
Use 0.9 or 0.8 for non convergent coupled-cluster calculations.

CC_SINGLE_PREC

CC_SINGLE_PREC
Precision selection for CCSD calculation. Available in CCMAN2 only.
TYPE:
INTEGER
DEFAULT:
0 double-precision calculation
OPTIONS:
1 single-precision calculation 2 single-precision calculation followed by double-precision clean-up iterations
RECOMMENDATION:
Do not set too tight convergence thresholds when using single precision

CC_SP_DM

CC_SP_DM
Precision selection for CCSD and EOM-CCSD intermediates, density matrices, gradients, and $S^{2}$
TYPE:
INTEGER
DEFAULT:
0 double-precision calculation
OPTIONS:
1 single-precision calculation
RECOMMENDATION:
NONE

CC_SP_E_CONV

CC_SP_E_CONV
Energy convergence criterion in single precision in CCSD calculations.
TYPE:
INTEGER
DEFAULT:
5
OPTIONS:
$n$ Corresponding to $10^{-n}$ convergence criterion
RECOMMENDATION:
Set 6 to be consistent with the default threshold in double precision in a pure single-precision calculation. When used with clean-up version, it should be smaller than double-precision threshold not to introduce extra iterations.

CC_SP_T_CONV

CC_SP_T_CONV
Amplitude convergence threshold in single precision in CCSD calculations.
TYPE:
INTEGER
DEFAULT:
3
OPTIONS:
$n$ Corresponding to $10^{-n}$ convergence criterion
RECOMMENDATION:
Set 4 to be consistent with the default threshold in double precision in a pure single-precision run. When used with clean-up version, it should be smaller than double-precision threshold not to introduce extra iterations.

CC_STATE_TO_OPT

CC_STATE_TO_OPT
Specifies which state to optimize.
TYPE:
INTEGER ARRAY
DEFAULT:
None
OPTIONS:
[$i$,$j$] optimize the $j$th state of the $i$th irrep.
RECOMMENDATION:
None

CC_SYMMETRY

CC_SYMMETRY
Activates point-group symmetry in the ADC calculation.
TYPE:
LOGICAL
DEFAULT:
TRUE If the system possesses any point-group symmetry.
OPTIONS:
TRUE Employ point-group symmetry FALSE Do not use point-group symmetry
RECOMMENDATION:
None

CC_THETA_CONV

CC_THETA_CONV
Convergence criterion on the RMS difference between successive sets of orbital rotation angles [$10^{-n}$].
TYPE:
INTEGER
DEFAULT:
OPTIONS:
$n$ $10^{-n}$ convergence criterion.
RECOMMENDATION:
Use default

Convergence desired on the RMS gradient of the energy with respect to orbital rotation angles [$10^{-n}$].
TYPE:
INTEGER
DEFAULT:
OPTIONS:
$n$ $10^{-n}$ convergence criterion.
RECOMMENDATION:
Use default

RMS orbital gradient threshold [$10^{-n}$] above which “mixed iterations” are performed in active space calculations if CC_ITERATE_OV is TRUE.
TYPE:
INTEGER
DEFAULT:
2
OPTIONS:
$n$ $10^{-n}$ threshold.
RECOMMENDATION:
Can be made smaller if convergence difficulties are encountered.

CC_THETA_STEPSIZE

CC_THETA_STEPSIZE
Scale factor for the orbital rotation step size. The optimal rotation steps should be approximately equal to the gradient vector.
TYPE:
INTEGER
DEFAULT:
$100$ Corresponding to 1.0
OPTIONS:
$abcde$ Integer code is mapped to $abc\times 10^{-de}$ If the initial step is smaller than 0.5, the program will increase step when gradients are smaller than the value of THETA_GRAD_THRESH, up to a limit of 0.5.
RECOMMENDATION:
Try a smaller value in cases of poor convergence and very large orbital gradients. For example, a value of 01001 translates to 0.1

CC_TRANS_PROP

CC_TRANS_PROP
Whether or not the transition dipole moment (in atomic units) and oscillator strength and rotatory strength (in atomic units) for the EOM-CCSD target states will be calculated. By default, the transition dipole moment, angular momentum matrix elements, and rotatory strengths are calculated between the CCSD reference and the EOM-CCSD target states. In order to calculate transition dipole moment, angular momentum matrix elements, and rotatory strengths between a set of EOM-CCSD states and another EOM-CCSD state, the CC_STATE_TO_OPT must be specified for this state.
TYPE:
INTEGER
DEFAULT:
0 (no transition properties will be calculated)
OPTIONS:
1 (calculate transition properties between all computed EOM state and the reference state) 2 (calculate transition properties between all pairs of EOM states)
RECOMMENDATION:
Additional equations (for the left EOM-CCSD eigenvectors plus lambda CCSD equations in case of transition properties between the CCSD reference and EOM-CCSD target states are requested) need to be solved for transition properties, approximately doubling the computational cost. The cost of the transition properties calculation itself is low.

CC_T_CONV

CC_T_CONV
Convergence criterion on the RMS difference between successive sets of coupled-cluster doubles amplitudes [$10^{-n}$]
TYPE:
INTEGER
DEFAULT:
OPTIONS:
$n$ $10^{-n}$ convergence criterion.
RECOMMENDATION:
Use default

CC_Z_CONV

CC_Z_CONV
Convergence criterion on the RMS difference between successive doubles $Z$-vector amplitudes [$10^{-n}$].
TYPE:
INTEGER
DEFAULT:
OPTIONS:
$n$ $10^{-n}$ convergence criterion.
RECOMMENDATION:
Use Default

CDFTCI_PRINT

CDFTCI_PRINT
Controls level of output from CDFT-CI procedure to Q-Chem output file.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Only print energies and coefficients of CDFT-CI final states 1 Level 0 plus CDFT-CI overlap, Hamiltonian, and population matrices 2 Level 1 plus eigenvectors and eigenvalues of the CDFT-CI population matrix 3 Level 2 plus promolecule orbital coefficients and energies
RECOMMENDATION:
Level 3 is primarily for program debugging; levels 1 and 2 may be useful for analyzing the coupling elements

CDFTCI_RESTART

CDFTCI_RESTART
To be used in conjunction with CDFTCI_STOP, this variable causes CDFT-CI to read already-converged states from disk and begin SCF convergence on later states. Note that the same $cdft section must be used for the stopped calculation and the restarted calculation. TYPE: INTEGER DEFAULT: 0 OPTIONS: $n$ Start calculations on state $n+1$ RECOMMENDATION: Use this setting in conjunction with CDFTCI_STOP. CDFTCI_SKIP_PROMOLECULES CDFTCI_SKIP_PROMOLECULES Skips promolecule calculations and allows fractional charge and spin constraints to be specified directly. TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: FALSE Standard CDFT-CI calculation is performed. TRUE Use the given charge/spin constraints directly, with no promolecule calculations. RECOMMENDATION: Setting to TRUE can be useful for scanning over constraint values. CDFTCI_STOP CDFTCI_STOP The CDFT-CI procedure involves performing independent SCF calculations on distinct constrained states. It sometimes occurs that the same convergence parameters are not successful for all of the states of interest, so that a CDFT-CI calculation might converge one of these diabatic states but not the next. This variable allows a user to stop a CDFT-CI calculation after a certain number of states have been converged, with the ability to restart later on the next state, with different convergence options. TYPE: INTEGER DEFAULT: 0 OPTIONS: $n$ Stop after converging state $n$ (the first state is state $1$) $0$ Do not stop early RECOMMENDATION: Use this setting if some diabatic states converge but others do not. CDFTCI_SVD_THRESH CDFTCI_SVD_THRESH By default, a symmetric orthogonalization is performed on the CDFT-CI matrix before diagonalization. If the CDFT-CI overlap matrix is nearly singular (i.e., some of the diabatic states are nearly degenerate), then this orthogonalization can lead to numerical instability. When computing $\mathbf{S}^{-1/2}$, eigenvalues smaller than $10^{-\mathrm{CDFTCI\_SVD\_THRESH}}$ are discarded. TYPE: INTEGER DEFAULT: 4 OPTIONS: $n$ for a threshold of $10^{-n}$. RECOMMENDATION: Can be decreased if numerical instabilities are encountered in the final diagonalization. CDFTCI CDFTCI Initiates a constrained DFT-configuration interaction calculation TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Perform a CDFT-CI Calculation FALSE No CDFT-CI RECOMMENDATION: Set to TRUE if a CDFT-CI calculation is desired. CDFT_BECKE_POP CDFT_BECKE_POP Whether the calculation should print the Becke atomic charges at convergence TYPE: LOGICAL DEFAULT: TRUE OPTIONS: TRUE Print populations FALSE Do not print them RECOMMENDATION: Use the default. Note that the Mulliken populations printed at the end of an SCF run will not typically add up to the prescribed constraint value. Only the Becke populations are guaranteed to satisfy the user-specified constraints. CDFT_LAMBDA_MODE CDFT_LAMBDA_MODE Allows CDFT potentials to be specified directly, instead of being determined as Lagrange multipliers. TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: FALSE Standard CDFT calculations are used. TRUE Instead of specifying target charge and spin constraints, use the values from the input deck as the value of the Becke weight potential RECOMMENDATION: Should usually be set to FALSE. Setting to TRUE can be useful to scan over different strengths of charge or spin localization, as convergence properties are improved compared to regular CDFT(-CI) calculations. CDFT_MAXITER CDFT_MAXITER Maximum number of iterations for converging the constraint. TYPE: INTEGER DEFAULT: 20 OPTIONS: N A maximum of N microiterations will be attempted. RECOMMENDATION: Default value is expected to be sufficient in most situations. CDFT_POP CDFT_POP Sets the charge partitioning scheme for cDFT or cDFT-CI jobs. TYPE: STRING DEFAULT: BECKE OPTIONS: BECKE Linear combination of atomic Becke functions FBH Fragment-based Hirshfeld partition RECOMMENDATION: None CDFT_POSTDIIS CDFT_POSTDIIS Controls whether the constraint is enforced after DIIS extrapolation. TYPE: LOGICAL DEFAULT: TRUE OPTIONS: TRUE Enforce constraint after DIIS FALSE Do not enforce constraint after DIIS RECOMMENDATION: Use the default unless convergence problems arise, in which case it may be beneficial to experiment with setting CDFT_POSTDIIS to FALSE. With this option set to TRUE, energies should be variational after the first iteration. CDFT_PREDIIS CDFT_PREDIIS Controls whether the constraint is enforced before DIIS extrapolation. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Enforce constraint before DIIS FALSE Do not enforce constraint before DIIS RECOMMENDATION: Use the default unless convergence problems arise, in which case it may be beneficial to experiment with setting CDFT_PREDIIS to TRUE. Note that it is possible to enforce the constraint both before and after DIIS by setting both CDFT_PREDIIS and CDFT_POSTDIIS to TRUE. CDFT_PRINT CDFT_PRINT Whether detailed information about CDFT iterations should be printed in the output file. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Print detailed information. FALSE Do not print detailed information. RECOMMENDATION: Use the default and invoke additional printing for troubleshooting. CDFT_THRESH CDFT_THRESH Threshold that determines how tightly the constraint must be satisfied. TYPE: INTEGER DEFAULT: 5 OPTIONS: N Constraint is satisfied to within $10^{-N}$. RECOMMENDATION: Default value is set to match SCF_CONVERGENCE. Use the default unless problems occur. CDFT CDFT Initiates a constrained DFT calculation TYPE: LOGICAL DEFAULT: FALSE OPTIONS: TRUE Perform a Constrained DFT Calculation FALSE No Density Constraint RECOMMENDATION: Set to TRUE if a Constrained DFT calculation is desired. CD_ALGORITHM CD_ALGORITHM Determines the algorithm for MP2 integral transformations. TYPE: STRING DEFAULT: Program determined. OPTIONS: DIRECT Uses fully direct algorithm (energies only). SEMI_DIRECT Uses disk-based semi-direct algorithm. LOCAL_OCCUPIED Alternative energy algorithm (see 6.4.1). RECOMMENDATION: Semi-direct is usually most efficient, and will normally be chosen by default. CFMM_ORDER CFMM_ORDER Controls the order of the multipole expansions in CFMM calculation. TYPE: INTEGER DEFAULT: 15 For single point SCF accuracy 25 For tighter convergence (optimizations) OPTIONS: $n$ Use multipole expansions of order $n$ RECOMMENDATION: Use the default. CHARGE_CHARGE_REPULSION CHARGE_CHARGE_REPULSION The repulsive Coulomb interaction parameter for YinYang atoms. TYPE: INTEGER DEFAULT: 550 OPTIONS: $n$ Use Q = $n\times 10^{-3}$ RECOMMENDATION: The repulsive Coulomb potential maintains bond lengths involving YinYang atoms with the potential $V(r)=Q/r$. The default is parameterized for carbon atoms. CHELPG_DX CHELPG_DX Sets the rectangular grid spacing for the traditional Cartesian ChElPG grid or the spacing between concentric Lebedev shells (when the variables CHELPG_HA and CHELPG_H are specified as well). TYPE: INTEGER DEFAULT: 6 OPTIONS: $N$ Corresponding to a grid space of $N/20$, in Å. RECOMMENDATION: Use the default, which corresponds to the “dense grid” of Breneman and Wiberg,132, unless the cost is prohibitive, in which case a larger value can be selected. Note that this default value is set with the Cartesian grid in mind and not the Lebedev grid. In the Lebedev case, a larger value can typically be used. CHELPG_HA CHELPG_HA Sets the Lebedev grid to use for non-hydrogen atoms. TYPE: INTEGER DEFAULT: NONE OPTIONS: $N$ Corresponding to a number of points in a Lebedev grid (see Section 5.5.2. RECOMMENDATION: None. CHELPG_HEAD CHELPG_HEAD Sets the “head space”132 (radial extent) of the ChElPG grid. TYPE: INTEGER DEFAULT: 30 OPTIONS: $N$ Corresponding to a head space of $N/10$, in Å. RECOMMENDATION: Use the default, which is the value recommended by Breneman and Wiberg.132 CHELPG_H CHELPG_H Sets the Lebedev grid to use for hydrogen atoms. TYPE: INTEGER DEFAULT: NONE OPTIONS: $N$ Corresponding to a number of points in a Lebedev grid. RECOMMENDATION: CHELPG_H must always be less than or equal to CHELPG_HA. If it is greater, it will automatically be set to the value of CHELPG_HA. CHELPG CHELPG Controls the calculation of CHELPG charges. TYPE: LOGICAL DEFAULT: FALSE OPTIONS: FALSE Do not calculate ChElPG charges. TRUE Compute ChElPG charges. RECOMMENDATION: Set to TRUE if desired. For large molecules, there is some overhead associated with computing ChElPG charges, especially if the number of grid points is large. CHILD_MP_ORDERS CHILD_MP_ORDERS The multipole orders included in the prepared FERFs. The last digit specifies how many multipoles to compute, and the digits in the front specify the multipole orders: 2: dipole (D); 3: quadrupole (Q); 4: octopole (O). Multipole order 1 is reserved for monopole FERFs which can be used to separate the effect of orbital contraction.674 TYPE: INTEGER DEFAULT: 0 OPTIONS: 21 D 232 DQ 2343 DQO RECOMMENDATION: Use 232 (DQ) when FERF is needed. CHILD_MP CHILD_MP Compute FERFs for fragments and use them as the basis for SCFMI calculations. TYPE: BOOLEAN DEFAULT: FALSE OPTIONS: FALSE Do not compute FERFs (use the full AO span of each fragment). TRUE Compute fragment FERFs. RECOMMENDATION: Use FERFs to compute polarization energy when large basis sets are used. In an “EDA2" calculation, this$rem variable is set based on the given option automatically.

CHOLESKY_TOL

CHOLESKY_TOL
Tolerance of Cholesky decomposition of two-electron integrals
TYPE:
INTEGER
DEFAULT:
3
OPTIONS:
$n$ Corresponds to a tolerance of $10^{-n}$
RECOMMENDATION:
2 - qualitative calculations, 3 - appropriate for most cases, 4 - quantitative (error in total energy typically less than 1 $\mu$hartree)

CISTR_PRINT

CISTR_PRINT
Controls level of output.
TYPE:
LOGICAL
DEFAULT:
FALSE Minimal output.
OPTIONS:
TRUE Increase output level.
RECOMMENDATION:
None

CIS_AMPL_ANAL

CIS_AMPL_ANAL
Perform additional analysis of CIS and TDDFT excitation amplitudes, including generation of natural transition orbitals, excited-state multipole moments, and Mulliken analysis of the excited state densities and particle/hole density matrices.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
RECOMMENDATION:
None

CIS_AMPL_PRINT

CIS_AMPL_PRINT
Sets the threshold for printing CIS and TDDFT excitation amplitudes.
TYPE:
INTEGER
DEFAULT:
15
OPTIONS:
$n$ Print if $|x_{ia}|$ or $|y_{ia}|$ is larger than $0.1\times n$.
RECOMMENDATION:
Use the default unless you want to see more amplitudes.

CIS_CONVERGENCE

CIS_CONVERGENCE
CIS is considered converged when error is less than $10^{-\mathrm{CIS\_CONVERGENCE}}$
TYPE:
INTEGER
DEFAULT:
6 CIS convergence threshold 10${}^{-6}$
OPTIONS:
$n$ Corresponding to $10^{-n}$
RECOMMENDATION:
None

CIS_DER_NUMSTATE

CIS_DER_NUMSTATE
Determines among how many states we calculate nonadiabatic couplings. These states must be specified in the \$derivative_coupling section.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
0 Do not calculate nonadiabatic couplings. $n$ Calculate $n(n-1)/2$ pairs of nonadiabatic couplings.
RECOMMENDATION:
None.

CIS_DIABATH_DECOMPOSE

CIS_DIABATH_DECOMPOSE
Decide whether or not to decompose the diabatic coupling into Coulomb, exchange, and one-electron terms.
TYPE:
LOGICAL
DEFAULT:
FALSE Do not decompose the diabatic coupling.
OPTIONS:
TRUE
RECOMMENDATION:
These decompositions are most meaningful for electronic excitation transfer processes. Currently, available only for CIS, not for TDDFT diabatic states.

CIS_DYNAMIC_MEM

CIS_DYNAMIC_MEM
Controls whether to use static or dynamic memory in CIS and TDDFT calculations.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE Partly use static memory TRUE Fully use dynamic memory
RECOMMENDATION:
The default control requires static memory (MEM_STATIC) sufficient to hold an array whose size grows by $2\times OV\times N_{\text{roots}}$ at each CIS iteration, where $N_{\text{roots}}$ is the number of unconverged roots ($\leq$ CIS_N_ROOTS). For a large calculation, one has to specify a large value for MEM_STATIC, which is not recommended (see Chapter 2). Therefore, it is recommended to use dynamic memory for large calculations.

CIS_GUESS_DISK_TYPE

CIS_GUESS_DISK_TYPE
Determines the type of guesses to be read from disk
TYPE:
INTEGER
DEFAULT:
Nil
OPTIONS:
RECOMMENDATION:
Must be specified if CIS_GUESS_DISK is TRUE.

CIS_GUESS_DISK

CIS_GUESS_DISK
Read the CIS guess from disk (previous calculation).
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE Create a new guess. TRUE Read the guess from disk.
RECOMMENDATION:
Requires a guess from previous calculation.

CIS_MOMENTS

CIS_MOMENTS
Controls calculation of excited-state (CIS or TDDFT) multipole moments.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE Do not calculate excited-state moments. TRUE Calculate moments for each excited state.
RECOMMENDATION:
Set to TRUE if excited-state moments are desired. (This is a trivial additional calculation.) The MULTIPOLE_ORDER controls how many multipole moments are printed.

CIS_MULLIKEN

CIS_MULLIKEN
Controls Mulliken and Löwdin population analyses for excited-state particle and hole density matrices.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE Do not perform particle/hole population analysis. TRUE Perform both Mulliken and Löwdin analysis of the particle and hole density matrices for each excited state.
RECOMMENDATION:
Set to TRUE if desired. This represents a trivial additional calculation.

CIS_N_ROOTS

CIS_N_ROOTS
Sets the number of excited state roots to find
TYPE:
INTEGER
DEFAULT:
0 Do not look for any excited states
OPTIONS:
$n$ $n>0$ Looks for $n$ excited states
RECOMMENDATION:
None

CIS_RELAXED_DENSITY

CIS_RELAXED_DENSITY
Use the relaxed CIS density for attachment/detachment density analysis as well as for for the general excited-state analysis of Section 10.2.9.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE Do not use the relaxed CIS density in analysis.