# CONSTRAINT

Section can be repeated.

specifies a linear constraint on the fitted charges. This can be used to give equal values to equivalent atoms. sum over atom_list c_i * q_i = t [Edit on GitHub]

## Keywords

- ATOM_COEF

- ATOM_LIST

- EQUAL_CHARGES

- TARGET

## Keyword descriptions

ATOM_COEF: real[ ]

  Usage: ATOM_COEF 1.0 -1.0

  Mentions: ⭐RESP Charges

  Defines the coefficient of the atom in this linear constraint [Edit on GitHub]

ATOM_LIST: integer[ ]

  Keyword can be repeated.

  Usage: ATOM_LIST 3 4

  Mentions: ⭐RESP Charges

  Defines the list of atoms involved in this constraint [Edit on GitHub]

EQUAL_CHARGES: logical = F

  Lone keyword: `T`

  Usage: EQUAL_CHARGES

  All atoms in ATOM_LIST are constrained to have the same charges. When using this keyword, TARGET and ATOM_COEF do not need to be set and will be ignored. Instead of using this keyword, the constraint section could be repeated. [Edit on GitHub]

TARGET: real = 0.00000000E+000

  Usage: TARGET 0.0

  Mentions: ⭐RESP Charges

  the target value for the constraint [Edit on GitHub]