DAVIDSON

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Keywords

Keyword descriptions

CONV_MOS_PERCENT

Type: real
Default: 5.00000000E-001
Usage: CONV_MOS_PERCENT 0.8

Description: Minimal percent of MOS that have to converge within the Davidson loop before the SCF iteration is completed and a new Hamiltonian is computed

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ENERGY_GAP

Type: real
Default: 2.00000000E-001
Usage: ENERGY_GAP 0.001

Description: Should be an estimate for the energy gap [a.u.] (HOMO-LUMO) and is used in preconditioning, especially effective with the FULL_ALL preconditioner, in which case it should be an underestimate of the gap (0.001 doing normally fine). For the other preconditioners, making this value larger (0.2) will tame the preconditioner in case of poor initial guesses.

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FIRST_PREC

Type: integer
Default: 1
Usage: FIRST_PREC 1

Description: First SCF iteration at which a Preconditioner is employed

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NEW_PREC_EACH

Type: integer
Default: 20
Usage: NEW_PREC_EACH 10

Description: Number of SCF iterations after which a new Preconditioner is computed

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PRECONDITIONER

Type: enum
Default: FULL_ALL
Usage: PRECONDITIONER FULL_ALL

Description: Type of preconditioner to be used with all minimization schemes.

Valid values:

  • FULL_ALL Most effective state selective preconditioner based on diagonalization

  • FULL_SINGLE_INVERSE Based on H-eS cholesky inversion, similar to FULL_SINGLE in preconditioning efficiency but cheaper to construct, might be somewhat less robust. Recommended for large systems.

  • NONE skip preconditioning

References: VandeVondele2003

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PRECOND_SOLVER

Type: enum
Default: DEFAULT
Usage: PRECOND_SOLVER DIRECT

Description: How the preconditioner is applied to the residual.

Valid values:

  • DEFAULT the default

  • DIRECT Cholesky decomposition followed by triangular solve (works for FULL_KINETIC/SINGLE_INVERSE/S_INVERSE)

  • INVERSE_CHOLESKY Cholesky decomposition followed by explicit inversion (works for FULL_KINETIC/SINGLE_INVERSE/S_INVERSE)

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SPARSE_MOS

Type: logical
Default: T
Lone keyword: T
Usage: SPARSE_MOS

Description: Use MOS as sparse matrix and avoid as much as possible multiplications with full matrices

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