MIXING

Define type and parameters for mixing procedures to be applied to the density matrix. Normally, only one type of mixing method should be accepted. The mixing procedures activated by this section are only active for diagonalization methods and linear scaling SCF, i.e. not with minimization methods based on OT. [Edit on GitHub]

Keywords

• SECTION_PARAMETERS

• ALPHA

• BETA

• BROY_W0

• BROY_WMAX

• BROY_WREF

• GMIX_P

• MAX_GVEC_EXP

• MAX_STEP

• METHOD

• NBUFFER

• NMIXING

• NSKIP

• N_SIMPLE_MIX

• PULAY_ALPHA

• PULAY_BETA

• REGULARIZATION

• R_FACTOR

Keyword descriptions

SECTION_PARAMETERS: logical = T

Lone keyword: T

Usage: &MIXING ON

Controls the activation of the mixing procedure [Edit on GitHub]

ALPHA: real = 4.00000000E-001

Usage: ALPHA 0.2

Mentions: ⭐Geometry Optimisation

Fraction of new density to be included [Edit on GitHub]

BETA: real = 5.00000000E-001 [bohr^-1]

Usage: BETA 1.5

Denominator parameter in Kerker damping introduced to suppress charge sloshing: rho_mix(g) = rho_in(g) + alphag^2/(g^2 + beta^2)(rho_out(g)-rho_in(g)) [Edit on GitHub]

BROY_W0: real = 1.00000000E-002

Usage: BROY_W0 0.03

w0 parameter used in Broyden mixing [Edit on GitHub]

BROY_WMAX: real = 3.00000000E+001

Usage: BROY_WMAX 10.0

[Edit on GitHub]

BROY_WREF: real = 1.00000000E+002

Usage: BROY_WREF 0.2

[Edit on GitHub]

GMIX_P: logical = F

Lone keyword: T

Usage: GMIX_P

Activate the mixing of the density matrix, using the same mixing coefficient applied for the g-space mixing. [Edit on GitHub]

MAX_GVEC_EXP: real = -1.00000000E+000

Usage: MAX_GVEC_EXP 3.

Restricts the G-space mixing to lower part of G-vector spectrum, up to a G0, by assigning the exponent of the Gaussian that can be represented by vectors smaller than G0 within a certain accuracy. [Edit on GitHub]

MAX_STEP: real = 1.00000000E-001

Usage: MAX_STEP .2

Upper bound for the magnitude of the unpredicted step size in the update by the multisecant mixing scheme [Edit on GitHub]

METHOD: enum = DIRECT_P_MIXING

Usage: METHOD KERKER_MIXING

Valid values:

• NONE No mixing is applied

• DIRECT_P_MIXING Direct mixing of new and old density matrices

• KERKER_MIXING Mixing of the potential in reciprocal space using the Kerker damping

• PULAY_MIXING Pulay mixing

• BROYDEN_MIXING Broyden mixing

• MULTISECANT_MIXING Multisecant scheme for mixing

Mixing method to be applied [Edit on GitHub]

NBUFFER: integer = 4

Aliases: NPULAY ,NBROYDEN ,NMULTISECANT

Usage: NBUFFER 2

Mentions: ⭐Geometry Optimisation

Number of previous steps stored for the actual mixing scheme [Edit on GitHub]

NMIXING: integer = 2

Usage: NMIXING 1

Minimal number of density mixing (should be greater than 0), before starting DIIS [Edit on GitHub]

NSKIP: integer = 0

Aliases: NSKIP_MIXING

Usage: NSKIP 10

Number of initial iteration for which the mixing is skipped [Edit on GitHub]

N_SIMPLE_MIX: integer = 0

Aliases: NSIMPLEMIX

Usage: NSIMPLEMIX

Number of kerker damping iterations before starting other mixing procedures [Edit on GitHub]

PULAY_ALPHA: real = 0.00000000E+000

Usage: PULAY_ALPHA 0.2

Fraction of new density to be added to the Pulay expansion [Edit on GitHub]

PULAY_BETA: real = 1.00000000E+000

Usage: PULAY_BETA 0.2

Fraction of residual contribution to be added to Pulay expansion [Edit on GitHub]

REGULARIZATION: real = 1.00000000E-005

Usage: REGULARIZATION 0.000001

Regularization parameter to stabilize the inversion of the residual matrix {Yn^t Yn} in the multisecant mixing scheme (noise) [Edit on GitHub]

R_FACTOR: real = 5.00000000E-002

Usage: R_FACTOR .12

Control factor for the magnitude of the unpredicted step size in the update by the multisecant mixing scheme [Edit on GitHub]