box command

Syntax

box keyword value ...
  • one or more keyword/value pairs may be appended

  • keyword = tilt

    tilt value = small or large
    

Examples

box tilt large
box tilt small

Description

Set attributes of the simulation box.

For triclinic (non-orthogonal) simulation boxes, the tilt keyword allows simulation domains to be created with arbitrary tilt factors, e.g. via the create_box or read_data commands. Tilt factors determine how skewed the triclinic box is; see the Howto triclinic doc page for a discussion of triclinic boxes in LAMMPS.

LAMMPS normally requires that no tilt factor can skew the box more than half the distance of the parallel box length, which is the 1st dimension in the tilt factor (x for xz). If tilt is set to small, which is the default, then an error will be generated if a box is created which exceeds this limit. If tilt is set to large, then no limit is enforced. You can create a box with any tilt factors you wish.

Note that if a simulation box has a large tilt factor, LAMMPS will run less efficiently, due to the large volume of communication needed to acquire ghost atoms around a processor’s irregular-shaped sub-domain. For extreme values of tilt, LAMMPS may also lose atoms and generate an error.

Restrictions

This command cannot be used after the simulation box is defined by a read_data or create_box command or read_restart command.

Related commands: none

Default

The default value is tilt = small.