OCC

Performs orbital-optimized MPn and CC computations and conventional MPn computations.

General

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

CCL_ENERGY

Do compute CC Lambda energy? In order to this option to be valid one should use “TPDM_ABCD_TYPE = COMPUTE” option.

CC_DIIS_MAX_VECS

Maximum number of vectors used in amplitude DIIS

  • Type: integer
  • Default: 6

CC_DIIS_MIN_VECS

Minimum number of vectors used in amplitude DIIS

  • Type: integer
  • Default: 2

CC_MAXITER

Maximum number of iterations to determine the amplitudes

  • Type: integer
  • Default: 50

CEPA_OS_SCALE

CEPA opposite-spin scaling value from SCS-CCSD

  • Type: double
  • Default: 1.27

CEPA_SOS_SCALE

CEPA Spin-opposite scaling (SOS) value

  • Type: double
  • Default: 1.3

CEPA_SS_SCALE

CEPA same-spin scaling value from SCS-CCSD

  • Type: double
  • Default: 1.13

CEPA_TYPE

CEPA type such as CEPA0, CEPA1 etc. currently we have only CEPA0.

  • Type: string
  • Possible Values: CEPA0
  • Default: CEPA0

CUTOFF

Cutoff value for numerical procedures

  • Type: integer
  • Default: 14

DO_DIIS

Do apply DIIS extrapolation?

DO_LEVEL_SHIFT

Do apply level shifting?

DO_SCS

Do perform spin-component-scaled OMP2 (SCS-OMP2)? In all computation, SCS-OMP2 energy is computed automatically. However, in order to perform geometry optimizations and frequency computations with SCS-OMP2, one needs to set ‘DO_SCS’ to true

DO_SOS

Do perform spin-opposite-scaled OMP2 (SOS-OMP2)? In all computation, SOS-OMP2 energy is computed automatically. However, in order to perform geometry optimizations and frequency computations with SOS-OMP2, one needs to set ‘DO_SOS’ to true

E3_SCALE

Scaling value for 3rd order energy correction (S. Grimme, Vol. 24, pp. 1529, J. Comput. Chem.)

  • Type: double
  • Default: 0.25

EA_POLES

Do compute OCC poles for electron affinities? Only valid for OMP2.

EKT_EA

Do compute virtual orbital energies based on extended Koopmans’ theorem?

EKT_IP

Do compute occupied orbital energies based on extended Koopmans’ theorem?

EP_EA_POLES

Do compute EP-OCC poles for electron affinities? Only valid for OMP2.

EP_IP_POLES

Do compute EP-OCC poles for ionization potentials? Only valid OMP2.

EP_MAXITER

Maximum number of electron propagator iterations.

  • Type: integer
  • Default: 30

E_CONVERGENCE

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

IP_POLES

Do compute OCC poles for ionization potentials? Only valid OMP2.

LEVEL_SHIFT

Level shift to aid convergence

  • Type: double
  • Default: 0.02

LINEQ_SOLVER

The solver will be used for simultaneous linear equations.

  • Type: string
  • Possible Values: CDGESV, FLIN, POPLE
  • Default: CDGESV

MAX_MOGRAD_CONVERGENCE

Convergence criterion for maximum orbital gradient

MOGRAD_DAMPING

Damping factor for the orbital gradient (Rendell et al., JCP, vol. 87, pp. 5976, 1987)

  • Type: double
  • Default: 1.0

MO_DIIS_NUM_VECS

Number of vectors used in orbital DIIS

  • Type: integer
  • Default: 6

MO_MAXITER

Maximum number of iterations to determine the orbitals

  • Type: integer
  • Default: 50

MO_READ

Do read coefficient matrices from external files of a previous OMP2 or OMP3 computation?

MO_STEP_MAX

Maximum step size in orbital-optimization procedure

  • Type: double
  • Default: 0.5

MO_WRITE

Do write coefficient matrices to external files for direct reading MOs in a subsequent job?

MP2_OS_SCALE

MP2 opposite-spin scaling value

  • Type: double
  • Default: 6.0/5.0

MP2_SOS_SCALE

MP2 Spin-opposite scaling (SOS) value

  • Type: double
  • Default: 1.3

MP2_SOS_SCALE2

Spin-opposite scaling (SOS) value for optimized-MP2 orbitals

  • Type: double
  • Default: 1.2

MP2_SS_SCALE

MP2 same-spin scaling value

  • Type: double
  • Default: 1.0/3.0

NAT_ORBS

Do compute natural orbitals?

OCC_ORBS_PRINT

Do print OCC orbital energies?

OEPROP

Do compute one electron properties?

OPT_METHOD

The optimization algorithm. Modified Steepest-Descent (MSD) takes a Newton-Raphson (NR) step with a crude approximation to diagonal elements of the MO Hessian. The ORB_RESP option obtains the orbital rotation parameters by solving the orbital-reponse (coupled-perturbed CC) equations. Additionally, for both methods a DIIS extrapolation will be performed with the DO_DIIS = TRUE option.

  • Type: string
  • Possible Values: MSD, ORB_RESP
  • Default: ORB_RESP

ORB_OPT

Do optimize the orbitals?

ORB_RESP_SOLVER

The algorithm will be used for solving the orbital-response equations. The LINEQ option create the MO Hessian and solve the simultaneous linear equations with method choosen by the LINEQ_SOLVER option. The PCG option does not create the MO Hessian explicitly, instead it solves the simultaneous equations iteratively with the preconditioned conjugate gradient method.

  • Type: string
  • Possible Values: PCG, LINEQ
  • Default: PCG

ORTH_TYPE

The algorithm for orthogonalization of MOs

  • Type: string
  • Possible Values: GS, MGS
  • Default: MGS

PCG_BETA_TYPE

Type of PCG beta parameter (Fletcher-Reeves or Polak-Ribiere).

  • Type: string
  • Possible Values: FLETCHER_REEVES, POLAK_RIBIERE
  • Default: FLETCHER_REEVES

PCG_CONVERGENCE

Convergence criterion for residual vector of preconditioned conjugate gradient method.

PCG_MAXITER

Maximum number of preconditioned conjugate gradient iterations.

  • Type: integer
  • Default: 30

RELAXED

Do consider orbital response contributions for PDMs and GFM?

RMS_MOGRAD_CONVERGENCE

Convergence criterion for RMS orbital gradient. Default adjusts depending on E_CONVERGENCE

R_CONVERGENCE

Convergence criterion for amplitudes (residuals).

SCS_TYPE

Type of the SCS method

  • Type: string
  • Possible Values: SCS, SCSN, SCSVDW, SCSMI
  • Default: SCS

SOS_TYPE

Type of the SOS method

  • Type: string
  • Possible Values: SOS, SOSPI
  • Default: SOS

SYMMETRIZE

Do symmetrize the GFM and OPDM in the EKT computations?

TPDM_ABCD_TYPE

How to take care of the TPDM VVVV-block. The COMPUTE option means it will be computed via an IC/OOC algoritm. The DIRECT option (default) means it will not be computed and stored, instead its contribution will be directly added to Generalized-Fock Matrix.

  • Type: string
  • Possible Values: DIRECT, COMPUTE
  • Default: DIRECT

WFN_TYPE

Type of the wavefunction.

  • Type: string
  • Possible Values: OMP2, OMP3, OCEPA, OMP2.5
  • Default: OMP2