ENFORCE_OCCUPATION

Enforce and control a special (initial) orbital occupation. Note, this feature works only for the methods MULLIKEN and LOWDIN. It should only be used to prepare an initial configuration. An inadequate parameter choice can easily inhibit SCF convergence. [Edit on GitHub]

Keywords

• SECTION_PARAMETERS

• EPS_SCF

• MAX_SCF

• NELEC

• ORBITALS

• SMEAR

Keyword descriptions

SECTION_PARAMETERS

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

Description: Controls the activation of the ENFORCE_OCCUPATION section

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EPS_SCF

Type: real
Default: 1.00000000E+030
Usage: EPS_SCF 0.001

Description: The occupation constraint is enforced until this threshold value for the SCF convergence criterion is reached

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MAX_SCF

Type: integer
Default: -1
Usage: MAX_SCF 5

Description: The occupation constraint is applied for this number of initial SCF iterations

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NELEC

Type: real[ ]
Default: 0.00000000E+000
Aliases: N_ELECTRONS
Usage: NELEC 5.0 4.0

Description: Number of alpha and beta electrons. An occupation (per spin) smaller than 0.5 is ignored.

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ORBITALS

Type: integer[ ]
Default: 0
Aliases: M
Usage: ORBITALS 0 +1 -1

Description: Select orbitals and occupation order. An input of 1 to 2*L+1 integer values in the range -L to L defining the M values of the spherical orbitals is expected.

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SMEAR

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

Description: The occupation constraint is applied with smearing

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