DCFT

Performs density cumulant functional theory computations

General

ALGORITHM

Algorithm to use for the density cumulant and orbital updates in the DCFT energy computation. Two-step algorithm is usually more efficient for small systems, but for large systems simultaneous algorithm (default) is recommended. If convergence problems are encountered (especially for highly symmetric systems) QC algorithm can be used.

  • Type: string
  • Possible Values: TWOSTEP, SIMULTANEOUS, QC
  • Default: SIMULTANEOUS

AO_BASIS

Controls whether to avoid the AO->MO transformation of the two-electron integrals for the four-virtual case (\(\langle VV|| VV \rangle\)) by computing the corresponding terms in the AO basis. AO_BASIS = DISK algorithm reduces the memory requirements and can significantly reduce the cost of the energy computation if SIMULTANEOUS algorithm is used. For the TWOSTEP algorithm, however, AO_BASIS = DISK option is not recommended due to extra I/O.

  • Type: string
  • Possible Values: NONE, DISK
  • Default: DISK

DCFT_FUNCTIONAL

Chooses appropriate DCFT method

  • Type: string
  • Possible Values: DC-06, DC-12, ODC-06, ODC-12, ODC-13, CEPA0
  • Default: ODC-12

DCFT_TYPE

What algorithm to use for the DCFT computation

  • Type: string
  • Possible Values: CONV, DF
  • Default: CONV

DF_BASIS_DCFT

Auxiliary basis set for DCFT density fitting computations. Defaults to a RI basis.

  • Type: string
  • Possible Values: basis string
  • Default: No Default

DIIS_START_CONVERGENCE

Value of RMS of the density cumulant residual and SCF error vector below which DIIS extrapolation starts. Same keyword controls the DIIS extrapolation for the solution of the response equations.

E_CONVERGENCE

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

GUESS_R_CONVERGENCE

Convergence criterion for the density cumulant and orbital guess for the variationally orbital-optimized DCFT methods. Currently only available for ALGORITHM = SIMULTANEOUS.

MAXITER

Maximum number of macro- or micro-iterations for both energy and response equations

  • Type: integer
  • Default: 40

MOLDEN_WRITE

Do write a MOLDEN output file? If so, the filename will end in .molden, and the prefix is determined by WRITER_FILE_LABEL (if set), or else by the name of the output file plus the name of the current molecule.

ODC_GUESS

Whether to perform a guess DC-06 or DC-12 computation for ODC-06 or ODC-12 methods, respectively. Currently only available for ALGORITHM = SIMULTANEOUS.

QC_COUPLING

Controls whether to include the coupling terms in the DCFT electronic Hessian (for ALOGRITHM = QC with QC_TYPE = SIMULTANEOUS only)

QC_TYPE

Controls the type of the quadratically-convergent algorithm (effective for ALGORITHM = QC). If set to TWOSTEP the Newton-Raphson equations are only solved for the orbital updates, the cumulant is updated using the standard Jacobi algorithm. If set to SIMULTANEOUS both cumulant and orbitals are updated in a single Newton-Raphson step.

  • Type: string
  • Possible Values: TWOSTEP, SIMULTANEOUS
  • Default: SIMULTANEOUS

REFERENCE

Reference wavefunction type

  • Type: string
  • Possible Values: UHF, RHF, ROHF
  • Default: RHF

RESPONSE_ALGORITHM

Algorithm to use for the solution of DC-06 response equations in computation of analytic gradients and properties

  • Type: string
  • Possible Values: TWOSTEP, SIMULTANEOUS
  • Default: TWOSTEP

R_CONVERGENCE

Convergence criterion for the RMS of the residual vector in density cumulant updates, as well as the solution of the density cumulant and orbital response equations. In the orbital updates controls the RMS of the SCF error vector

THREE_PARTICLE

Whether to compute three-particle energy correction or not

  • Type: string
  • Possible Values: NONE, PERTURBATIVE
  • Default: NONE

Expert

CACHELEVEL

Controls how to cache quantities within the DPD library

  • Type: integer
  • Default: 2

DAMPING_PERCENTAGE

The amount (percentage) of damping to apply to the orbital update procedure: 0 will result in a full update, 100 will completely stall the update. A value around 20 (which corresponds to 20% of the previous iteration’s density being mixed into the current iteration) can help in cases where oscillatory convergence is observed.

  • Type: double
  • Default: 0.0

DCFT_GUESS

Whether to read the orbitals from a previous computation, or to compute an MP2 guess

  • Type: string
  • Possible Values: CC, BCC, MP2, DCFT
  • Default: MP2

DIIS_MAX_VECS

Maximum number of error vectors stored for DIIS extrapolation

  • Type: integer
  • Default: 6

DIIS_MIN_VECS

Minimum number of error vectors stored for DIIS extrapolation

  • Type: integer
  • Default: 3

ENERGY_LEVEL_SHIFT

Level shift applied to the diagonal of the density-weighted Fock operator. While this shift can improve convergence, it does change the DCFT energy.

  • Type: double
  • Default: 0.0

IGNORE_TAU

Controls whether to ignore terms containing non-idempotent contribution to OPDM or not (for debug puproses only). For practical applications only the default must be used

INTS_TOLERANCE

Minimum absolute value below which integrals are neglected

MO_RELAX

Controls whether to relax the orbitals during the energy computation or not (for debug puproses only). For practical applications only the default must be used

ORBITAL_LEVEL_SHIFT

The shift applied to the denominator in the orbital update iterations

  • Type: double
  • Default: 0.0

RELAX_GUESS_ORBITALS

Controls whether to relax the guess orbitals by taking the guess density cumulant and performing orbital update on the first macroiteration (for ALOGRITHM = TWOSTEP only)

RELAX_TAU

Controls whether to relax tau during the cumulant updates or not

STABILITY_ADD_VECTORS

The number of vectors that can be added simultaneously into the subspace for Davidson’s diagonalization in stability check

  • Type: integer
  • Default: 20

STABILITY_AUGMENT_SPACE_TOL

The value of the rms of the residual in Schmidt orthogonalization which is used as a threshold for augmenting the vector subspace in stability check

STABILITY_CHECK

Performs stability analysis of the DCFT energy

STABILITY_CONVERGENCE

Controls the convergence of the Davidson’s diagonalization in stability check

STABILITY_MAX_SPACE_SIZE

The maximum size of the subspace for the stability check. The program will terminate if this parameter is exceeded and the convergence (STABILITY_CONVERGENCE) is not satisfied

  • Type: integer
  • Default: 200

STABILITY_N_EIGENVALUES

The number of Hessian eigenvalues computed during the stability check

  • Type: integer
  • Default: 3

STABILITY_N_GUESS_VECTORS

The number of guess vectors used for Davidson’s diagonalization in stability check

  • Type: integer
  • Default: 20

TIKHONOW_OMEGA

The shift applied to the denominator in the density cumulant update iterations

  • Type: double
  • Default: 0.0