4.3.2 Job Control

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.; one of the correlated methods listed in Sections 7.10,  7.11, and  7.9;
RECOMMENDATION:
       In general, consult the literature to guide your selection. Our recommendations for DFT are indicated in bold in Section 5.3.5.

BASIS
       Specifies the 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.

GEN_SCFMAN
       Use GEN_SCFMAN for the present SCF calculation.
TYPE:
       BOOLEAN
DEFAULT:
       TRUE
OPTIONS:
       FALSE Use the previous SCF code. TRUE Use GEN_SCFMAN.
RECOMMENDATION:
       Set to FALSE in cases where features not yet supported by GEN_SCFMAN are needed.

ORBITAL_ENERGY_PREC
       Obtain additional digits of precision in the orbital energies.
TYPE:
       INTEGER
DEFAULT:
       0
OPTIONS:
       0 Standard printout with 4 decimal digits (in Hartree). 1 5 decimal digits. 2 Scientific notation with 10 digits of precision.
RECOMMENDATION:
       Set as desired. Has no effect in cases where the orbital symmetry labels are printed; use SYM_IGNORE = TRUE if additional precision is needed in such cases.

PRINT_ORBITALS
       Prints orbital coefficients with atom labels in analysis part of output.
TYPE:
       INTEGER/LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       FALSE Do not print any orbitals. TRUE Prints occupied orbitals plus 5 virtual orbitals. NVIRT Number of virtual orbitals to print.
RECOMMENDATION:
       Use true unless more virtual orbitals are desired.

SCF_CONVERGENCE
       SCF is considered converged when the wave function error is less that ${10}^{-\mathrm{SCF}\mathrm{\_}\mathrm{CONVERGENCE}}$. Adjust the value of THRESH at the same time.
TYPE:
       INTEGER
DEFAULT:
       5 For single point energy calculations (including BSSE and XSAPT jobs). 7 For job types NMR, STATPOLAR, DYNPOLAR, HYPERPOLAR, and ISSC. 8 For most other job types, including geometry optimization, transition-state search, vibrational analysis, CIS/TDDFT calculations, correlated wavefunction methods, energy decomposition analysis (EDA2), etc.
OPTIONS:
       User-defined
RECOMMENDATION:
       Tighter criteria are recommended for geometry optimization and vibration analysis. Larger values provide more significant figures, at greater computational cost. Beginning with Q-Chem 3.0, the DIIS error is measured by the maximum error rather than the RMS error that was used in earlier versions.

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:
       Use the default unless ROHF is desired. 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).

OS_ROSCF
       Run an open-shell singlet ROSCF calculation with GEN_SCFMAN.
TYPE:
       BOOLEAN
DEFAULT:
       FALSE
OPTIONS:
       TRUE OS_ROSCF calculation is performed. FALSE Do not run OS_ROSCF (it will run a closed-shell RSCF calculation instead).
RECOMMENDATION:
       Set to TRUE if desired.

ROSCF_DODS
       Run a canonical restricted open-shell calculation (also called “ROSCF-DODS”, where DODS stands for different orbitals for different spins) with GEN_SCFMAN. Available for high-spin half-filled open-shell systems.
TYPE:
       BOOLEAN
DEFAULT:
       FALSE
OPTIONS:
       TRUE Perform a canonical ROSCF calculation. FALSE Do not perform a canonical ROSCF calculation (run an open-shell USCF calculation instead).
RECOMMENDATION:
       Set to TRUE if desired.

GHF
       Run a generalized Hartree-Fock calculation with GEN_SCFMAN.
TYPE:
       BOOLEAN
DEFAULT:
       FALSE
OPTIONS:
       TRUE Run a GHF calculation. FALSE Do not use GHF.
RECOMMENDATION:
       Set to TRUE if desired.

COMPLEX
       Run an SCF calculation with complex MOs using GEN_SCFMAN.
TYPE:
       BOOLEAN
DEFAULT:
       FALSE
OPTIONS:
       TRUE Use complex orbitals. FALSE Use real orbitals.
RECOMMENDATION:
       Set to TRUE if desired.

COMPLEX_MIX
       Mix a certain percentage of the real part of the HOMO to the imaginary part of the LUMO.
TYPE:
       INTEGER
DEFAULT:
       0
OPTIONS:
       0–100 The mix angle = $\pi \cdot$COMPLEX_MIX/100.
RECOMMENDATION:
       It may help find the stable complex solution (similar idea as SCF_GUESS_MIX).