OUTER_SCF

Controls an outer SCF loop, often used to stabilize difficult OT convergence, constraints, or other variables wrapped around the inner SCF cycle. [Edit on GitHub]

Mentions: ⭐How to make a SCF run converge

Subsections

Keywords

Keyword descriptions

SECTION_PARAMETERS

Type: logical
Default: F
Lone keyword: T
Usage: &OUTER_SCF ON

Description: Activates the outer SCF loop. [Edit on GitHub]

BISECT_TRUST_COUNT

Type: integer
Default: 10
Usage: BISECT_TRUST_COUNT 5

Description: Maximum number of times the same point will be used in bisection, a small number guards against the effect of wrongly converged states. [Edit on GitHub]

DIIS_BUFFER_LENGTH

Type: integer
Default: 3
Usage: DIIS_BUFFER_LENGTH 5

Description: Maximum number of DIIS vectors used [Edit on GitHub]

EPS_SCF

Type: real
Default: 1.00000000E-005
Usage: EPS_SCF 1.0E-6

Description: The target gradient of the outer SCF variables. Notice that the EPS_SCF of the inner loop also determines the value that can be reached in the outer loop, typically EPS_SCF of the outer loop must be smaller than or equal to EPS_SCF of the inner loop. [Edit on GitHub]

EXTRAPOLATION_ORDER

Type: integer
Default: 3
Usage: EXTRAPOLATION_ORDER 5

Description: Number of past states used in the extrapolation of the variables during e.g. MD [Edit on GitHub]

MAX_SCF

Type: integer
Default: 50
Usage: MAX_SCF 20

Description: Maximum number of outer SCF loops. [Edit on GitHub]

Mentions: ⭐How to make a SCF run converge

OPTIMIZER

Type: enum
Default: NONE
Usage: OPTIMIZER SD

Description: Method used to bring the outer loop to a stationary point [Edit on GitHub]

Valid values:

  • SD Takes steps in the direction of the gradient, multiplied by step_size

  • DIIS Uses a Direct Inversion in the Iterative Subspace method

  • NONE Do nothing, useful only with the none type

  • BISECT Bisection of the gradient, useful for difficult one dimensional cases

  • BROYDEN Broyden’s method. Variant defined in BROYDEN_TYPE.

  • NEWTON Newton’s method. Only compatible with CDFT constraints.

  • SECANT Secant method. Only for one dimensional cases. See Broyden for multidimensional cases.

  • NEWTON_LS Newton’s method with backtracking line search to find the optimal step size. Only compatible with CDFT constraints. Starts from the regular Newton solution and successively reduces the step size until the L2 norm of the CDFT gradient decreases or MAX_LS steps is reached. Potentially very expensive because each iteration performs a full SCF calculation.

STEP_SIZE

Type: real
Default: 5.00000000E-001
Usage: STEP_SIZE -1.0

Description: The initial step_size used in the optimizer (currently steepest descent). Note that in cases where a sadle point is sought for (constrained DFT), this can be negative. For Newton and Broyden optimizers, use a value less/higher than the default 1.0 (in absolute value, the sign is not significant) to active an under/overrelaxed optimizer. [Edit on GitHub]

TYPE

Type: enum
Default: NONE
Usage: TYPE DDAPC_CONSTRAINT

Description: Specifies which kind of outer SCF should be employed [Edit on GitHub]

Valid values:

  • DDAPC_CONSTRAINT Enforce a constraint on the DDAPC, requires the corresponding section

  • S2_CONSTRAINT Enforce a constraint on the S2, requires the corresponding section

  • BASIS_CENTER_OPT Optimize positions of basis functions, if atom types FLOATING_BASIS_CENTER are defined

  • CDFT_CONSTRAINT Enforce a constraint on a generic CDFT weight population. Requires the corresponding section QS&CDFT which determines the type of weight used.

  • NONE Do nothing in the outer loop, useful for resetting the inner loop,