# DEFINE_REGION

Section can be repeated.

This section provides the possibility to define arbitrary region for the MSD calculation. [Edit on GitHub]

## Keywords

- LIST

- MM_SUBSYS

- MOLNAME

- QM_SUBSYS

## Keyword descriptions

LIST: integer[ ]

  Keyword can be repeated.

  Usage: LIST {integer} {integer} .. {integer}

  Specifies a list of atoms to thermostat. [Edit on GitHub]

MM_SUBSYS: enum = NONE

  Aliases: PROTEIN

  Usage: MM_SUBSYS (NONE|ATOMIC|MOLECULAR)

  Valid values:

  - `NONE` Thermostat nothing

  - `ATOMIC` Only the MM atoms itself

  - `MOLECULAR` The full molecule/residue that contains a MM atom

  In a QM/MM run all MM atoms are specified as a whole ensemble to be thermostated [Edit on GitHub]

MOLNAME: string[ ]

  Keyword can be repeated.

  Aliases: SEGNAME

  Usage: MOLNAME WAT MEOH

  Specifies the name of the molecules to thermostat [Edit on GitHub]

QM_SUBSYS: enum = NONE

  Usage: QM_SUBSYS (NONE|ATOMIC|MOLECULAR)

  Valid values:

  - `NONE` Thermostat nothing

  - `ATOMIC` Only the QM atoms itself

  - `MOLECULAR` The full molecule/residue that contains a QM atom

  In a QM/MM run all QM atoms are specified as a whole ensemble to be thermostated [Edit on GitHub]