The librassf module can be enabled by setting EXCHANGE = HF, CORRELATION = RASCI2, and LIBRASSF = 1 in the $rem variable section. One should also indicate the number of roots by setting RAS_N_ROOTS appropriately. Although the module is called through RASCI2, most job control options are more similar to those found in RASCI1, with the exception of RAS_N_ROOTS.
The number of spin-flips and IP/EA are determined by the $rem variables RASSF_DELTA_ALPHA (the number of alpha electrons removed) and RASSF_DELTA_BETA (the number of beta electrons added). Hole and particle excitations can be added by setting the RAS_DO_HOLE and RAS_DO_PART keywords. Additionally, text files containing eigenvalues and eigenvectors can be printed via the RASSF_WRITE_EVALS and RASSF_WRITE_EVECS keywords.
RAS_N_ROOTS
RAS_N_ROOTS
Sets the number of RAS-CI roots to be computed.
TYPE:
INTEGER
DEFAULT:
None
OPTIONS:
Compute RAS-CI states
RECOMMENDATION:
None.
RASSF_DELTA_ALPHA
RASSF_DELTA_ALPHA
Sets the number of alpha electrons to remove relative to the reference.
TYPE:
INTEGER
DEFAULT:
None
OPTIONS:
Remove no alpha electrons (use for EA)
Remove one alpha electron (use for 1SF, IP)
Remove two alpha electrons (use for 2SF, 1SF-IP)
RECOMMENDATION:
None.
RASSF_DELTA_BETA
RASSF_DELTA_BETA
Sets the number of beta electrons to add relative to the reference.
TYPE:
INTEGER
DEFAULT:
None
OPTIONS:
Add no beta electrons (use for IP)
Add one beta electron (use for 1SF, EA)
Add two beta electrons (use for 2SF, 1SF-EA)
RECOMMENDATION:
None.
RAS_DO_HOLE
RAS_DO_HOLE
Enables hole excitations.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
No hole excitations (use for CAS or RAS(p))
Single hole excitations (use for RAS(h) or RAS(h,p))
RECOMMENDATION:
None.
RAS_DO_PART
RAS_DO_PART
Enables particle excitations.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
No particle excitations (use for CAS or RAS(h))
Single particle excitations (use for RAS(p) or RAS(h,p))
RECOMMENDATION:
None.
N_FROZEN_CORE
N_FROZEN_CORE
Number of frozen core orbitals.
TYPE:
SIZE_T
DEFAULT:
0
OPTIONS:
Number of frozen core orbitals.
RECOMMENDATION:
None.
N_FROZEN_VIRTUAL
N_FROZEN_VIRTUAL
Number of frozen virtual orbitals.
TYPE:
SIZE_T
DEFAULT:
0
OPTIONS:
Number of frozen virtual orbitals.
RECOMMENDATION:
None.
RASSF_GUESS
RASSF_GUESS
Determines which initial set of guess vectors to use for Davidson.
TYPE:
INTEGER
DEFAULT:
OPTIONS:
Random orthonormal guess (default for CAS)
Identity guess
CAS guess (default for RAS)
RECOMMENDATION:
Starting from a CAS guess is recommended for larger molecules. If Davidson
encounters issues with linearly dependent eigenvectors, consider using identity.
The random orthonormal guess requires building a large matrix and is therefore
only recommended for calculations with fewer determinants.
RASSF_WRITE_EVALS
RASSF_WRITE_EVALS
Determines whether to write eigenvalues to an output file.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
Do not write eigenvalues to an output file
Write eigenvalues to an output file
RECOMMENDATION:
None.
RASSF_WRITE_EVECS
RASSF_WRITE_EVECS
Determines whether to write eigenvectors to an output file.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
Do not write eigenvectors to an output file
Write eigenvectors to an output file
RECOMMENDATION:
None.
CAS_LOCAL
CAS_LOCAL
Determines whether to do localization.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
No localization
Boys localization
Pipek-Mezey localization
RECOMMENDATION:
None.
CAS_LOCAL_ALGO
CAS_LOCAL_ALGO
Passed into localizer. Set to 1 if doing Boys localization.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
No localization
Boys localization
Pipek-Mezey localization
RECOMMENDATION:
None.
RASSF_DO_BLOCH
RASSF_DO_BLOCH
Determines whether to do effective Hamiltonian analysis.
TYPE:
INTEGER
DEFAULT:
0
OPTIONS:
Skip analysis
Do effective Hamiltonian analysis
RECOMMENDATION:
None.