7.2.8 Basic CIS Job Control Options‣ 7.2 Uncorrelated Wave Function Methods ‣ Chapter 7 Open-Shell and Excited-State Methods ‣ Q-Chem 6.1 User’s Manual

CIS-type jobs are requested by setting the $rem variable EXCHANGE = HF and CORRELATION = NONE, as in a ground-state Hartree-Fock calculation, but then also specifying a number of excited-state roots using the $rem keyword CIS_N_ROOTS.

Note: For RHF case, $n$ singlets and $n$ triplets will be computed, unless specified otherwise by using CIS_TRIPLETS and CIS_SINGLETS.

CIS_N_ROOTS

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

CIS_SINGLETS

CIS_SINGLETS
       Solve for singlet excited states in RCIS calculations (ignored for UCIS).
TYPE:
       LOGICAL
DEFAULT:
       TRUE
OPTIONS:
       TRUE Solve for singlet states. FALSE Do not solve for singlet states.
RECOMMENDATION:
       None

CIS_TRIPLETS

CIS_TRIPLETS
       Solve for triplet excited states in RCIS calculations (ignored for UCIS).
TYPE:
       LOGICAL
DEFAULT:
       TRUE
OPTIONS:
       TRUE Solve for triplet states. FALSE Do not solve for triplet states.
RECOMMENDATION:
       None

RPA

RPA
       Do an RPA calculation in addition to a CIS or TDDFT/TDA calculation.
TYPE:
       LOGICAL/INTEGER
DEFAULT:
       FALSE
OPTIONS:
       FALSE Do not do an RPA calculation. TRUE Do an RPA calculation. 2 Do an RPA calculation without running CIS or TDDFT/TDA first.
RECOMMENDATION:
       RPA = 2 is not available for restricted open-shell wavefunctions.

CIS_STATE_DERIV

CIS_STATE_DERIV
       Sets CIS state for excited state optimizations and vibrational analysis.
TYPE:
       INTEGER
DEFAULT:
       0 Does not select any of the excited states.
OPTIONS:
       $n$ Select the $n$ th state.
RECOMMENDATION:
       Check to see that the states do not change order during an optimization, due to state crossings.

SPIN_FLIP

SPIN_FLIP
       Selects whether to perform a standard excited state calculation, or a spin-flip calculation. Spin multiplicity should be set to 3 for systems with an even number of electrons, and 4 for systems with an odd number of electrons.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE/FALSE
RECOMMENDATION:
       None

SPIN_FLIP_XCIS

SPIN_FLIP_XCIS
       Do a SF-XCIS calculation.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       FALSE Do not do an SF-XCIS calculation. TRUE Do an SF-XCIS calculation (requires ROHF triplet ground state).
RECOMMENDATION:
       None

SFX_AMP_OCC_A

SFX_AMP_OCC_A
       Defines a custom amplitude guess vector in SF-XCIS method.
TYPE:
       INTEGER
DEFAULT:
       0
OPTIONS:
       $n$ builds a guess amplitude with an $\alpha$ -hole in the $n$ th orbital (requires SFX_AMP_VIR_B).
RECOMMENDATION:
       Only use when default guess is not satisfactory.

SFX_AMP_VIR_B

SFX_AMP_VIR_B
       Defines a user-specified amplitude guess vector in SF-XCIS method.
TYPE:
       INTEGER
DEFAULT:
       0
OPTIONS:
       $n$ builds a guess amplitude with a $\beta$ -particle in the $n$ th orbital (requires SFX_AMP_OCC_A).
RECOMMENDATION:
       Only use when default guess is not satisfactory.

XCIS

XCIS
       Do an XCIS calculation in addition to a CIS calculation.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       FALSE Do not do an XCIS calculation. TRUE Do an XCIS calculation (requires ROHF ground state).
RECOMMENDATION:
       None

SASF_CIS

SASF_CIS
       Do an SA-SF-CIS/DFT calculation.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       FALSE Do not do an SA-SF-CIS/DFT calculation. TRUE Do an SA-SF-CIS/DFT calculation (requires ROHF ground state).
RECOMMENDATION:
       None

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7.2.8 Basic CIS Job Control Options