12 Fragment-Based Methods

12.6 Job Control for Locally-Projected SCF Methods

(May 16, 2021)

FRGM_METHOD
       Specifies a locally-projected method.
TYPE:
       STRING
DEFAULT:
       NONE
OPTIONS:
       STOLL Locally-projected SCF equations of Stoll are solved. GIA Locally-projected SCF equations of Gianinetti are solved. NOSCF_RS Single Roothaan-step correction to the FRAGMO initial guess. NOSCF_ARS Approximate single Roothaan-step correction to the FRAGMO initial guess. NOSCF_DRS Double Roothaan-step correction to the FRAGMO initial guess. NOSCF_RS_FOCK Non-converged SCF energy of the single Roothaan-step MOs.
RECOMMENDATION:
       STOLL and GIA are for variational optimization of the ALMOs. NOSCF options are for computationally fast corrections of the FRAGMO initial guess.

FRGM_LPCORR
       Specifies a correction method performed after the locally-projected equations are converged.
TYPE:
       STRING
DEFAULT:
       NONE
OPTIONS:
       ARS Approximate Roothaan-step perturbative correction. RS Single Roothaan-step perturbative correction. EXACT_SCF Full SCF variational correction. ARS_EXACT_SCF Both ARS and EXACT_SCF in a single job. RS_EXACT_SCF Both RS and EXACT_SCF in a single job.
RECOMMENDATION:
       For large basis sets use ARS, use RS if ARS fails.

SCF_PRINT_FRGM
       Controls the output of Q-Chem jobs on isolated fragments.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE The output is printed to the parent job output file. FALSE The output is not printed.
RECOMMENDATION:
       Use TRUE if details about isolated fragments are important.

EDA_BSSE
       Calculates the BSSE correction when performing the energy decomposition analysis.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE/FALSE
RECOMMENDATION:
       Set to TRUE unless a very large basis set is used.

EDA_COVP
       Perform COVP analysis when evaluating the RS or ARS charge-transfer correction. COVP analysis is currently implemented only for systems of two fragments.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE/FALSE
RECOMMENDATION:
       Set to TRUE to perform COVP analysis in an EDA or SCF MI(RS) job.

EDA_PRINT_COVP
       Replace the final MOs with the CVOP orbitals in the end of the run.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE/FALSE
RECOMMENDATION:
       Set to TRUE to print COVP orbitals instead of conventional MOs.

NVO_LIN_MAX_ITE
       Maximum number of iterations in the preconditioned conjugate gradient solver of the single-excitation amplitude equations.
TYPE:
       INTEGER
DEFAULT:
       30
OPTIONS:
       n User–defined number of iterations.
RECOMMENDATION:
       None.

NVO_LIN_CONVERGENCE
       Target error factor in the preconditioned conjugate gradient solver of the single-excitation amplitude equations.
TYPE:
       INTEGER
DEFAULT:
       3
OPTIONS:
       n User–defined number.
RECOMMENDATION:
       Solution of the single-excitation amplitude equations is considered converged if the maximum residual is less than 10-n multiplied by the current DIIS error. For the ARS correction, n is automatically set to 1 since the locally-projected DIIS error is normally several orders of magnitude smaller than the full DIIS error.

NVO_METHOD
       Sets method to be used to converge solution of the single-excitation amplitude equations.
TYPE:
       INTEGER
DEFAULT:
       9
OPTIONS:
       n User–defined number.
RECOMMENDATION:
       This is an experimental option. Use the default.

NVO_UVV_PRECISION
       Controls convergence of the Taylor series when calculating the Uvv block from the single-excitation amplitudes. Series is considered converged when the maximum element of the term is less than 10-n.
TYPE:
       INTEGER
DEFAULT:
       11
OPTIONS:
       n User–defined number.
RECOMMENDATION:
       NVO_UVV_PRECISION must be the same as or larger than THRESH.

NVO_UVV_MAXPWR
       Controls convergence of the Taylor series when calculating the Uvv block from the single-excitation amplitudes. If the series is not converged at the nth term, more expensive direct inversion is used to calculate the Uvv block.
TYPE:
       INTEGER
DEFAULT:
       10
OPTIONS:
       n User–defined number.
RECOMMENDATION:
       None.

NVO_TRUNCATE_DIST
       Specifies which atomic blocks of the Fock matrix are used to construct the preconditioner.
TYPE:
       INTEGER
DEFAULT:
       -1
OPTIONS:
       n>0 If distance between a pair of atoms is more than n Ångstroms do not include the atomic block. -2 Do not use distance threshold, use NVO_TRUNCATE_PRECOND instead. -1 Include all blocks. 0 Include diagonal blocks only.
RECOMMENDATION:
       This option does not affect the final result. However, it affects the rate of the PCG algorithm convergence. For small systems, use the default.

NVO_TRUNCATE_PRECOND
       Specifies which atomic blocks of the Fock matrix are used to construct the preconditioner. This variable is used only if NVO_TRUNCATE_DIST is set to -2.
TYPE:
       INTEGER
DEFAULT:
       2
OPTIONS:
       n If the maximum element in an atomic block is less than 10-n do not include the block.
RECOMMENDATION:
       Use the default. Increasing n improves convergence of the PCG algorithm but overall may slow down calculations.