# 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: logical = F

  Lone keyword: `T`

  Usage: &ENFORCE_OCCUPATION ON

  Controls the activation of the ENFORCE_OCCUPATION section [Edit on GitHub]

EPS_SCF: real = 1.00000000E+030

  Usage: EPS_SCF 0.001

  The occupation constraint is enforced until this threshold value for the SCF convergence criterion is reached [Edit on GitHub]

MAX_SCF: integer = -1

  Usage: MAX_SCF 5

  The occupation constraint is applied for this number of initial SCF iterations [Edit on GitHub]

NELEC: real[ ] = 0.00000000E+000

  Aliases: N_ELECTRONS

  Usage: NELEC 5.0 4.0

  Number of alpha and beta electrons. An occupation (per spin) smaller than 0.5 is ignored. [Edit on GitHub]

ORBITALS: integer[ ] = 0

  Aliases: M

  Usage: ORBITALS 0 +1 -1

  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. [Edit on GitHub]

SMEAR: logical = F

  Lone keyword: `T`

  Usage: SMEAR ON

  The occupation constraint is applied with smearing [Edit on GitHub]