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(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 ${U}_{vv}$ 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 ${U}_{vv}$ block
from the single-excitation amplitudes. If the series is not converged at the
$n$th term, more expensive direct inversion is used to calculate the ${U}_{vv}$
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.