RESPONSE_SOLVER

References: VandeVondele2012

Specifies the parameters of the linear scaling solver routines [Edit on GitHub]

Keywords

Keyword descriptions

EPS: real = 1.00000000E-012

Usage: EPS 1.e-10

Target accuracy for the convergence of the conjugate gradient. [Edit on GitHub]

EPS_FILTER: real = 1.00000000E-010

Usage: EPS_FILTER 1.0E-10

Threshold used for filtering matrix operations. [Edit on GitHub]

EPS_LANCZOS: real = 1.00000000E-003

Usage: EPS_LANCZOS 1.0E-4

Threshold used for lanczos estimates. [Edit on GitHub]

MATRIX_CLUSTER_TYPE: enum = ATOMIC

Usage: MATRIX_CLUSTER_TYPE MOLECULAR

Valid values:

  • ATOMIC Using atomic blocks

  • MOLECULAR Using molecular blocks.

Specify how atomic blocks should be clustered in the used matrices, in order to improve flop rate, and possibly speedup the matrix multiply. Note that the atomic s_preconditioner can not be used. Furthermore, since screening is on matrix blocks, slightly more accurate results can be expected with molecular. [Edit on GitHub]

MAX_ITER: integer = 50

Usage: MAX_ITER 200

Maximum number of conjugate gradient iteration to be performed for one optimization. [Edit on GitHub]

MAX_ITER_LANCZOS: integer = 128

Usage: MAX_ITER_LANCZOS 128

Maximum number of lanczos iterations. [Edit on GitHub]

METHOD: enum = AO_ORTHO

Usage: METHOD SOLVER

Valid values:

  • MO_SOLVER Solver based on MO (vector) formalism

  • AO_ORTHO Solver based on density matrix formalism

Algorithm used to solve response equation. Both solver are conjugate gradient based, but use either a vector (MO-coefficient) or density matrix formalism in the orthonormal AO-basis to obtain response density [Edit on GitHub]

PRECONDITIONER: enum = MULTI_LEVEL

Usage: PRECONDITIONER FULL_ALL

Valid values:

  • FULL_ALL Most effective state selective preconditioner based on diagonalization, requires the ENERGY_GAP parameter to be an underestimate of the HOMO-LUMO gap. This preconditioner is recommended for almost all systems, except very large systems where make_preconditioner would dominate the total computational cost.

  • 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.

  • FULL_SINGLE Based on H-eS diagonalisation, not as good as FULL_ALL, but somewhat cheaper to apply.

  • FULL_KINETIC Cholesky inversion of S and T, fast construction, robust, and relatively good, use for very large systems.

  • FULL_S_INVERSE Cholesky inversion of S, not as good as FULL_KINETIC, yet equally expensive.

  • MULTI_LEVEL Based on same CG as AO-solver itself, but uses cheaper linear transformation

  • NONE skip preconditioning

Type of preconditioner to be used with MO conjugate gradient solver. They differ in effectiveness, cost of construction, cost of application. Properly preconditioned minimization can be orders of magnitude faster than doing nothing. Only multi-level conjugate gradient preconditioner (MULTI_LEVEL) available for AO response solver (AO_ORTHO). [Edit on GitHub]

RESTART: logical = F

Lone keyword: T

Usage: RESTART

Restart the response calculation if the restart file exists [Edit on GitHub]

RESTART_EVERY: integer = 50

Usage: RESTART_EVERY 50

Restart the conjugate gradient after the specified number of iterations. [Edit on GitHub]

S_INVERSION: enum = SIGN_SQRT

Usage: S_PRECONDITIONER MOLECULAR

Valid values:

  • SIGN_SQRT Using the inverse sqrt as obtained from sign function iterations.

  • HOTELLING Using the Hotellign iteration.

Method used to compute the inverse of S. [Edit on GitHub]

S_PRECONDITIONER: enum = ATOMIC

Usage: S_PRECONDITIONER MOLECULAR

Valid values:

  • NONE No preconditioner

  • ATOMIC Using atomic blocks

  • MOLECULAR Using molecular sub-blocks. Recommended if molecules are defined and not too large.

Preconditions S with some appropriate form. [Edit on GitHub]

S_SQRT_METHOD: enum = NEWTONSCHULZ

Usage: S_SQRT_METHOD NEWTONSCHULZ

Valid values:

  • NEWTONSCHULZ Using a Newton-Schulz-like iteration

  • PROOT Using the p-th root method.

Method for the caclulation of the sqrt of S. [Edit on GitHub]

S_SQRT_ORDER: integer = 3

Aliases: SIGN_SQRT_ORDER

Usage: S_SQRT_ORDER 3

Order of the iteration method for the calculation of the sqrt of S. [Edit on GitHub]