CCENERGY¶

Computes coupled cluster energies. Called as part of any coupled cluster computation.

General¶

ABCD¶

Type: string

Possible Values: NEW, OLD

Default: NEW

ANALYZE¶

Do ?

Type: boolean

Default: false

BRUECKNER_ORBS_R_CONVERGENCE¶

Convergence criterion for Breuckner orbitals. The convergence is determined based on the largest $T_1$ amplitude.

Type: conv double

Default: 1e-5

CACHELEVEL¶

Cacheing level for libdpd governing the storage of amplitudes, integrals, and intermediates in the CC procedure. A value of 0 retains no quantities in cache, while a level of 6 attempts to store all quantities in cache. For particularly large calculations, a value of 0 may help with certain types of memory problems. The default is 2, which means that all four-index quantites with up to two virtual-orbital indices (e.g., $\langle ij | ab \rangle>$ integrals) may be held in the cache.

Type: integer

Default: 2

CACHETYPE¶

Selects the priority type for maintaining the automatic memory cache used by the libdpd codes. A value of LOW selects a “low priority” scheme in which the deletion of items from the cache is based on pre-programmed priorities. A value of LRU selects a “least recently used” scheme in which the oldest item in the cache will be the first one deleted.

Type: string

Possible Values: LOW, LRU

Default: LOW

CC_NUM_THREADS¶

Number of threads

Type: integer

Default: 1

CC_OS_SCALE¶

Type: double

Default: 1.27

CC_SS_SCALE¶

Type: double

Default: 1.13

DIIS¶

Do use DIIS extrapolation to accelerate convergence?

Type: boolean

Default: true

LOCAL¶

Do simulate the effects of local correlation techniques?

Type: boolean

Default: false

LOCAL_CUTOFF¶

Value (always between one and zero) for the Broughton-Pulay completeness check used to contruct orbital domains for local-CC calculations. See J. Broughton and P. Pulay, J. Comp. Chem. 14, 736-740 (1993) and C. Hampel and H.-J. Werner, J. Chem. Phys. 104, 6286-6297 (1996).

Type: double

Default: 0.02

LOCAL_METHOD¶

Type of local-CCSD scheme to be simulated. WERNER selects the method developed by H.-J. Werner and co-workers, and AOBASIS selects the method developed by G.E. Scuseria and co-workers (currently inoperative).

Type: string

Possible Values: WERNER, AOBASIS

Default: WERNER

LOCAL_PAIRDEF¶

Type: string

Possible Values: BP, RESPONSE

Default: BP

LOCAL_WEAKP¶

Desired treatment of “weak pairs” in the local-CCSD method. A value of NEGLECT ignores weak pairs entirely. A value of NONE treats weak pairs in the same manner as strong pairs. A value of MP2 uses second-order perturbation theory to correct the local-CCSD energy computed with weak pairs ignored.

Type: string

Possible Values: NONE, NEGLECT, MP2

Default: NONE

MAXITER¶

Maximum number of iterations to solve the CC equations

Type: integer

Default: 50

MP2_AMPS_PRINT¶

Do print the MP2 amplitudes which are the starting guesses for RHF and UHF reference functions?

Type: boolean

Default: false

MP2_OS_SCALE¶

Type: double

Default: 1.20

MP2_SS_SCALE¶

Type: double

Default: 1.0/3.0

NEW_TRIPLES¶

Do ?

Type: boolean

Default: true

NUM_AMPS_PRINT¶

Number of important $t_1$ and $t_2$ amplitudes to print

Type: integer

Default: 10

PAIR_ENERGIES_PRINT¶

Do print MP2 and CCSD pair energies for RHF references?

Type: boolean

Default: false

PROPERTY¶

Type: string

Possible Values: POLARIZABILITY, ROTATION, MAGNETIZABILITY, ROA, ALL

Default: POLARIZABILITY

REFERENCE¶

Reference wavefunction type

Type: string

Possible Values: RHF, ROHF, UHF

Default: RHF

RESTART¶

Do restart the coupled-cluster iterations from old $t_1$ and $t_2$ amplitudes? For geometry optimizations, Brueckner calculations, etc. the iterative solution of the CC amplitude equations may benefit considerably by reusing old vectors as initial guesses. Assuming that the MO phases remain the same between updates, the CC codes will, by default, re-use old vectors, unless the user sets RESTART = false.

Type: boolean

Default: true

R_CONVERGENCE¶

Convergence criterion for wavefunction (change) in CC amplitude equations.

Type: conv double

Default: 1e-7

SCSN_MP2¶

Do ?

Type: boolean

Default: false

SCS_CCSD¶

Do ?

Type: boolean

Default: false

SCS_MP2¶

Do ?

Type: boolean

Default: false

SEMICANONICAL¶

Convert ROHF MOs to semicanonical MOs

Type: boolean

Default: true

SPINADAPT_ENERGIES¶

Do print spin-adapted pair energies?

Type: boolean

Default: false

T2_COUPLED¶

Do ?

Type: boolean

Default: false

T3_WS_INCORE¶

Do ?

Type: boolean

Default: false

Expert¶

AO_BASIS¶

The algorithm to use for the $\left<VV||VV\right>$ terms If AO_BASIS is NONE, the MO-basis integrals will be used; if AO_BASIS is DISK, the AO-basis integrals stored on disk will be used; if AO_BASIS is DIRECT, the AO-basis integrals will be computed on the fly as necessary. NB: The DIRECT option is not fully implemented and should only be used by experts. Default is NONE. Note: The developers recommend use of this keyword only as a last resort because it significantly slows the calculation. The current algorithms for handling the MO-basis four-virtual-index integrals have been significantly improved and are preferable to the AO-based approach.

Type: string

Possible Values: NONE, DISK, DIRECT

Default: NONE

FORCE_RESTART¶

Do restart the coupled-cluster iterations even if MO phases are screwed up?

Type: boolean

Default: false

WFN¶

Wavefunction type

Type: string

Possible Values: CCSD, CCSD_T, EOM_CCSD, LEOM_CCSD, BCCD, BCCD_T, CC2, CC3, EOM_CC2, EOM_CC3, CCSD_MVD

Default: NONE

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