# QPARM

Section to define the Q parameter (crystalline order parameter) as a collective variable. [Edit on GitHub]

Subsections

- POINT

## Keywords

- ATOMS_FROM

- ATOMS_TO

- INCLUDE_IMAGES

- L

- RCUT

- RSTART

## Keyword descriptions

ATOMS_FROM: integer[ ]

  Keyword can be repeated.

  Aliases: POINTS_FROM

  Usage: ATOMS_FROM {integer} {integer} ..

  Specify indexes of atoms/points building the coordination variable. [Edit on GitHub]

ATOMS_TO: integer[ ]

  Keyword can be repeated.

  Aliases: POINTS_TO

  Usage: ATOMS_TO {integer} {integer} ..

  Specify indexes of atoms/points building the coordination variable. [Edit on GitHub]

INCLUDE_IMAGES: logical = F

  Lone keyword: `T`

  Usage: INCLUDE_IMAGES

  Whether to include periodic images of ATOMS_TO into the neighbor list. [Edit on GitHub]

L: integer

  Usage: L {integer}

  Specifies the L spherical harmonics from Ylm. [Edit on GitHub]

RCUT: real = [angstrom]

  Usage: RCUT {real}

  Specifies the distance cutoff for neighbors. Cutoff function is exactly zero for all neighbors beyond RCUT. [Edit on GitHub]

RSTART: real = [angstrom]

  Usage: RSTART {real}

  Specifies the distance cutoff for neighbors. Cutoff function is exactly 1 for all neighbors closer than RSTART. [Edit on GitHub]