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7.12 Restricted Active Space Spin-Flip (RAS-SF) and Configuration Interaction (RAS-CI)

7.12.12 Job Control Options for casman

(December 20, 2021)

In casman, the built-in methods can be run by simply setting the value of CORRELATION accordingly:

CORRELATION

CORRELATION
       Sets the pre-defined method to use for casman.
TYPE:
       STRING
DEFAULT:
       None.
OPTIONS:
       SF-CAS CAS-SF with no perturbative corrections (or a custom method) SF-CAS(h,p) CAS-SF with perturbative corrections for hole (h) and particle (p) excitations SF-CAS(S) CAS-SF with perturbative corrections for single (h,p,hp) excitations SF-CAS(2x) CAS-SF with perturbative corrections for 2x (h,p,hp,hh,pp) excitations SF-CAS(3x) CAS-SF with perturbative corrections for 3x (h,p,hp,hh,pp,hhp,hpp) excitations SF-CAS(3x)+D CAS-SF with perturbative corrections for (h,p,hp,hh,pp,hhp,hpp) + MP2 RAS1->RAS3 double excitations
RECOMMENDATION:
       None.

If a custom excitation scheme is required, one can set CORRELATION = SF-CAS and set the following variables manually. (If you are using one of the built-in methods, setting these variables manually should be avoided, since they are automatically set up appropriately by Q-Chem if CORRELATION is not SF-CAS.)

RAS_N_SPIN_FLIP

RAS_N_SPIN_FLIP
       Sets the number of spin-flips.
TYPE:
       INTEGER
DEFAULT:
       Maximum number of spin-flips (n=(α-β)/2)
OPTIONS:
       n Do n spin-flips
RECOMMENDATION:
       None.

CAS_DO_NDPT

CAS_DO_NDPT
       Do non-degenerate perturbation theory?
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Do non-degenerate perturbation theory. FALSE Do not use non-degenerate perturbation theory.
RECOMMENDATION:
       None.

CAS_QDPT_ORDER

CAS_QDPT_ORDER
       Order of terms kept in the quasi-degenerate perturbation theory denominator expansion.
TYPE:
       INTEGER
DEFAULT:
       None.
OPTIONS:
       n Keep terms of order n in the denominator expansion.
RECOMMENDATION:
       None.

CAS_DO_1X

CAS_DO_1X
       Do perturbative hole (h) and particle (p) correction?
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Do perturbative hole (h) and particle (p) correction FALSE Do not do perturbative hole (h) and particle (p) correction
RECOMMENDATION:
       None.

CAS_DO_SINGLES

CAS_DO_SINGLES
       Do perturbative singles (h,p,hp) correction?
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Do perturbative singles correction FALSE Do not do perturbative singles correction
RECOMMENDATION:
       None.

CAS_DO_2x

CAS_DO_2x
       Do perturbative 2x (h,p,hp,hh,pp) correction?
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Do perturbative 2x correction FALSE Do not do perturbative 2x correction
RECOMMENDATION:
       None.

CAS_DO_3x

CAS_DO_3x
       Do perturbative 3x (h,p,hp,hh,pp,hhp,hpp) correction?
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Do perturbative 3x correction FALSE Do not do perturbative 3x correction
RECOMMENDATION:
       None.

CAS_DO_DOUBLES

CAS_DO_DOUBLES
       Do perturbative (h,p,hp,hh,pp,hhp,hpp) correction + MP2 RAS1->RAS3 doubles?
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Do perturbative (h,p,hp,hh,pp,hhp,hpp) + MP2 RAS1->RAS3 doubles correction FALSE Do not do the correction
RECOMMENDATION:
       None.

CAS_LEVEL_SHIFT

CAS_LEVEL_SHIFT
       Use a denominator level-shift?
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Use the denominator level-shift FALSE Do not use the denominator level-shift
RECOMMENDATION:
       None.

CAS_SPARSE

CAS_SPARSE
       Use a sparse matrix multiply when forming the effective Hamiltonian?
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Use sparse matrix multiply in forming effective Hamiltonian FALSE Do not use sparse matrix multiply in forming effective Hamiltonian
RECOMMENDATION:
       None. Can be useful for larger numbers of spin-flips.