MOM

References: Gilbert2008, Barca2018

Define type and parameters for the maximum overlap method (MOM) to determine orbital occupancies. The MOM procedures activated by this section are only active for diagonalization methods, i.e. not with minimization methods based on OT. Incompatible with core-level excitation spectra (XAS). [Edit on GitHub]

Keyword descriptions

SECTION_PARAMETERS

Type: logical
Default: F
Lone keyword: T
Usage: MOM ON

Description: Controls the activation of the MOM procedure

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DEOCC_ALPHA

Type: integer[ ]
Default: 0
Usage: DEOCC_ALPHA 10 11 …

Description: Alpha orbitals to be deoccupied

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DEOCC_BETA

Type: integer[ ]
Default: 0
Usage: DEOCC_BETA 10 11 …

Description: Beta orbitals to be deoccupied

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MOM_TYPE

Type: enum
Default: MOM
Usage: MOM_TYPE mom

Description: Revision of the maximum overlap method to be used

Valid values:

MOM Originally proposed MOM protocol which uses molecular orbitals from the previous SCF cycle as reference
IMOM Initial-MOM which uses molecular orbitals of the initial guess as reference

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OCC_ALPHA

Type: integer[ ]
Default: 0
Usage: OCC_ALPHA 12 15 …

Description: Alpha orbitals to be occupied

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OCC_BETA

Type: integer[ ]
Default: 0
Usage: OCC_BETA 12 15 …

Description: Beta orbitals to be occupied

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PROJ_FORMULA

Type: enum
Default: NORM
Usage: PROJ_FORMULA norm

Description: Projection formula to be used

Valid values:

NORM The one which ignores the phase of molecular orbitals: proj_j = \sqrt(\sum_i overlap(i, j)^2)
SUM The one proposed in the original paper: proj_j = |\sum_i overlap(i, j)|

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START_ITER

Type: integer
Default: 0
Usage: START_ITER 2

Description: SCF iteration cycle to start the MOM procedure. Could be used for ground state calculations only in order to stabilise oscillating SCF iterations

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