CCENERGY

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

General

ABCD

Type of ABCD algorithm will be used

  • Type: string
  • Possible Values: NEW, OLD
  • Default: NEW

ANALYZE

Do analyze T2 amplitudes

BCCD_MAXITER

Convert ROHF MOs to semicanonical MOs

  • Type: integer
  • Default: 50

BRUECKNER_ORBS_R_CONVERGENCE

Convergence criterion for Brueckner orbitals. The convergence is determined based on the largest \(T_1\) amplitude. Default adjusts depending on E_CONVERGENCE

CACHELEVEL

Caching 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 quantities 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

Coupled-cluster opposite-spin scaling value

  • Type: double
  • Default: 1.27

CC_SS_SCALE

Coupled-cluster same-spin scaling value

  • Type: double
  • Default: 1.13

DIIS

Do use DIIS extrapolation to accelerate convergence?

E_CONVERGENCE

Convergence criterion for energy. See Table Post-SCF Convergence for default convergence criteria for different calculation types.

LOCAL

Do simulate the effects of local correlation techniques?

LOCAL_CPHF_CUTOFF

Cutoff value for local-coupled-perturbed-Hartree-Fock

  • Type: double
  • Default: 0.10

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

Definition of local pair domains, default is BP, Boughton-Pulay.

  • 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?

MP2_OS_SCALE

MP2 opposite-spin scaling value

  • Type: double
  • Default: 1.20

MP2_SS_SCALE

MP2 same-spin scaling value

  • Type: double
  • Default: 1.0

NEW_TRIPLES

Do use new triples?

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?

PROPERTY

The response property desired. Acceptable values are POLARIZABILITY (default) for dipole-polarizabilities, ROTATION for specific rotations, ROA for Raman Optical Activity, and ALL for all of the above.

  • 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.

R_CONVERGENCE

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

SCSN_MP2

Do SCS-MP2 with parameters optimized for nucleic acids?

SCS_CCSD

Do spin-component-scaled CCSD

SCS_MP2

Do spin-component-scaled MP2 (SCS-MP2)?

SEMICANONICAL

Convert ROHF MOs to semicanonical MOs

SPINADAPT_ENERGIES

Do print spin-adapted pair energies?

T2_COUPLED

T3_WS_INCORE

Do build W intermediates required for cc3 in core memory?

Expert

AO_BASIS

The algorithm to use for the \(\left\langle VV||VV\right\rangle\) 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?

WFN

Wavefunction type

  • Type: string
  • Default: NONE