# CONSTRAINT

Section specifying information regarding how to impose constraints on the system. [Edit on GitHub]

Subsections

- COLLECTIVE
- COLVAR_RESTART
- CONSTRAINT_INFO
- FIXED_ATOMS
- FIX_ATOM_RESTART
- G3X3
- G4X6
- HBONDS
- LAGRANGE_MULTIPLIERS
- VIRTUAL_SITE

## Keywords

- CONSTRAINT_INIT

- PIMD_BEADWISE_CONSTRAINT

- ROLL_TOLERANCE

- SHAKE_TOLERANCE

## Keyword descriptions

CONSTRAINT_INIT: logical = F

  Lone keyword: `T`

  Usage: CONSTRAINT_INIT <LOGICAL>

  Apply constraints to the initial position and velocities. Default is to apply constraints only after the first MD step. [Edit on GitHub]

PIMD_BEADWISE_CONSTRAINT: logical = F

  Lone keyword: `T`

  Usage: PIMD_BEADWISE_CONSTRAINT <LOGICAL>

  Apply beadwise constraints to PIMD. [Edit on GitHub]

ROLL_TOLERANCE: real = 1.00000000E-010 [internal_cp2k]

  Aliases: ROLL_TOL ,ROLL

  Usage: ROLL_TOLERANCE <REAL>

  Set the tolerance for the roll constraint algorithm. [Edit on GitHub]

SHAKE_TOLERANCE: real = 1.00000000E-006 [internal_cp2k]

  Aliases: SHAKE_TOL ,SHAKE

  Usage: SHAKE_TOLERANCE <REAL>

  Set the tolerance for the shake/rattle constraint algorithm. [Edit on GitHub]