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B.1 Text Input Summary

B.1.3 $rem Variable List

(May 7, 2024)

B.1.3.1 Overview

The general format of the $rem input for Q-Chem text input files is simply as follows:

$rem
   rem_variable   rem_option   [comment]
   rem_variable   rem_option   [comment]
$end

This input is not case sensitive. The following sections contain the names and options of available $rem variables for users. The format for describing each $rem variable is as follows:

REM_VARIABLE

REM_VARIABLE
       A short description of what the variable controls
TYPE:
       Defines the variable as either INTEGER, LOGICAL or STRING.
DEFAULT:
       Describes Q-Chem’s internal default, if any exists.
OPTIONS:
       Lists options available for the user
RECOMMENDATION:
       Gives a quick recommendation.

B.1.3.2 General

BASIS BASIS_LIN_DEP_THRESH
EXCHANGE CORRELATION
ECP JOBTYPE
METHOD PURECART

B.1.3.3 SCF Control

BASIS2 BASISPROJTYPE
DIIS_PRINT DIIS_SUBSPACE_SIZE
DIRECT_SCF INCFOCK
MAX_DIIS_CYCLES MAX_SCF_CYCLES
PSEUDO_CANONICAL SCF_ALGORITHM
SCF_CONVERGENCE SCF_FINAL_PRINT
SCF_GUESS SCF_GUESS_MIX
SCF_GUESS_PRINT SCF_PRINT
THRESH THRESH_DIIS_SWITCH
UNRESTRICTED VARTHRESH
S2THRESH

B.1.3.4 DFT Options

CORRELATION EXCHANGE
FAST_XC INC_DFT
INCDFT_DENDIFF_THRESH INCDFT_GRIDDIFF_THRESH
INCDFT_DENDIFF_VARTHRESH INCDFT_GRIDDIFF_VARTHRESH
XC_GRID XC_SMART_GRID

B.1.3.5 Large Molecules

CFMM_ORDER DIRECT_SCF
EPAO_ITERATE EPAO_WEIGHTS
GRAIN INCFOCK
INTEGRAL_2E_OPR INTEGRALS_BUFFER
LIN_K MEM_STATIC
MEM_TOTAL METECO
OMEGA PAO_ALGORITHM
PAO_METHOD THRESH
VARTHRESH RI_J
RI_K ARI
ARI_R0 ARI_R1
S2THRESH

B.1.3.6 Correlated Methods

AO2MO_DISK CD_ALGORITHM
CORE_CHARACTER CORRELATION
MEM_STATIC MEM_TOTAL
N_FROZEN_CORE N_FROZEN_VIRTUAL
PRINT_CORE_CHARACTER

B.1.3.7 Correlated Methods Handled by CCMAN and CCMAN2

Most of these $rem variables that start CC_.

These are relevant for CCSD and other CC methods (OD, VOD, CCD, QCCD, CCVB-SD, etc).

CC_CANONIZE CC_RESTART_NO_SCF
CC_T_CONV CC_DIIS_SIZE
CC_DIIS_FREQ CC_DIIS_START
CC_DIIS_MAX_OVERLAP CC_DIIS_MIN_OVERLAP
CC_RESTART CC_SAVEAMPL

These options are only relevant to methods involving orbital optimization (OOCD, VOD, QCCD, VQCCD):

CC_MP2NO_GUESS CC_MP2NO_GRAD
CC_DIIS CC_DIIS12_SWITCH
CC_THETA_CONV CC_THETA_GRAD_CONV
CC_THETA_STEPSIZE CC_RESET_THETA
CC_THETA_GRAD_THRESH CC_HESS_THRESH
CC_ED_CCD CC_QCCD_THETA_SWITCH
CC_PRECONV_T2Z CC_PRECONV_T2Z_EACH
CC_PRECONV_FZ CC_ITERATE_OV
CC_CANONIZE_FREQ CC_CANONIZE_FINAL

Properties and optimization:

CC_REF_PROP CC_REF_PROP_TE
CC_FULLRESPONSE

B.1.3.8 Perfect Pairing, Coupled-Cluster Valence-Bond, and Related Methods

CCVB_METHOD CCVB_GUESS
GVB_N_PAIRS GVB_LOCAL
GVB_ORB_MAX_ITER GVB_RESTART
GVB_ORB_CONV GVB_ORB_SCALE
GVB_AMP_SCALE GVB_DO_SANO
GVB_PRINT

B.1.3.9 Excited States: CIS, TDDFT, SF-XCIS and SOS-CIS(D)

CIS_CONVERGENCE CIS_GUESS_DISK
CIS_GUESS_DISK_TYPE CIS_N_ROOTS
CIS_RELAXED_DENSITY CIS_SINGLETS
CIS_STATE_DERIV CIS_TRIPLETS
MAX_CIS_CYCLES RPA
XCIS SPIN_FLIP_XCIS

B.1.3.10 Excited States: EOM-CC and CI Methods

Those are keywords relevant to EOM-CC and CI methods handled by CCMAN/CCMAN2. Most of these $rem variables that start CC_ and EOM_.

EOM_DAVIDSON_CONVERGENCE EOM_DAVIDSON_MAXVECTORS
EOM_DAVIDSON_THRESHOLD EOM_DAVIDSON_MAX_ITER
EOM_NGUESS_DOUBLES EOM_NGUESS_SINGLES
EOM_DOEXDIAG EOM_PRECONV_DOUBLES
EOM_PRECONV_SINGLES EOM_PRECONV_SD
EOM_IPEA_FILTER EOM_FAKE_IPEA
CC_REST_AMPL CC_REST_TRIPLES
CC_EOM_PROP CC_TRANS_PROP
CC_STATE_TO_OPT CC_EOM_PROP
CC_EOM_PROP_TE CC_FULLRESPONSE