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.

Type: boolean

Default: false

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?

Type: boolean

Default: true

DO_LEVEL_SHIFT¶

Do apply level shifting?

Type: boolean

Default: true

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

Type: boolean

Default: false

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

Type: boolean

Default: false

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.

Type: boolean

Default: false

EKT_EA¶

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

Type: boolean

Default: false

EKT_IP¶

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

Type: boolean

Default: false

EP_EA_POLES¶

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

Type: boolean

Default: false

EP_IP_POLES¶

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

Type: boolean

Default: false

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.

Type: conv double

Default: 1e-8

IP_POLES¶

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

Type: boolean

Default: false

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

Type: conv double

Default: 1e-3

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?

Type: boolean

Default: false

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?

Type: boolean

Default: false

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

MP2_TYPE¶

Algorithm to use for non-OO MP2 computation

Type: string

Possible Values: DF, CONV

Default: DF

NAT_ORBS¶

Do compute natural orbitals?

Type: boolean

Default: false

OCC_ORBS_PRINT¶

Do print OCC orbital energies?

Type: boolean

Default: false

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?

Type: boolean

Default: true

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.

Type: conv double

Default: 1e-6

PCG_MAXITER¶

Maximum number of preconditioned conjugate gradient iterations.

Type: integer

Default: 30

RMS_MOGRAD_CONVERGENCE¶

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

Type: conv double

Default: 1e-6

R_CONVERGENCE¶

Convergence criterion for amplitudes (residuals).

Type: conv double

Default: 1e-5

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

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

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