# HBONDS

This section is used to set bonds constraints involving Hydrogen atoms [Edit on GitHub]

Subsections

- RESTRAINT

## Keywords

- ATOM_TYPE

- EXCLUDE_MM

- EXCLUDE_QM

- MOLECULE

- MOLNAME

- TARGETS

## Keyword descriptions

ATOM_TYPE: string[ ]

  Usage: ATOM_TYPE <CHARACTER>

  Defines the atoms’ type forming a bond with an hydrogen. If not specified the default bond value of the first molecule is used as constraint target [Edit on GitHub]

EXCLUDE_MM: logical = F

  Lone keyword: `T`

  Usage: EXCLUDE_MM <LOGICAL>

  Does not shake HBONDS in the MM region within a QM/MM calculation [Edit on GitHub]

EXCLUDE_QM: logical = F

  Lone keyword: `T`

  Usage: EXCLUDE_QM <LOGICAL>

  Does not shake HBONDS in the QM region within a QM/MM calculation [Edit on GitHub]

MOLECULE: integer[ ]

  Usage: MOLECULE {integer} .. {integer}

  Specifies the indexes of the molecule kind (in input file order) on which the constraint will be applied. MOLECULE and MOLNAME keyword exclude themself mutually. [Edit on GitHub]

MOLNAME: string[ ]

  Aliases: SEGNAME

  Usage: MOLNAME {character} .. {character}

  Specifies the names of the molecule on which the constraint will be applied. [Edit on GitHub]

TARGETS: real[ ] = [internal_cp2k]

  Usage: TARGETS {real} {real} {real}

  The constrained distances’ values for the types defines in ATOM_TYPE. [Edit on GitHub]