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### fix coord/original command

Syntax:

    fix ID group-ID coord/original

- ID, group-ID are documented in fix command
- coord/original = style name of this fix command

Examples:

    fix 1 all coord/original

Description:

Store the original coordinates of atoms in the group at the time the fix command is issued. This is useful for computing a displacement of the atoms at later times, via the compute displace/atom command. Or the original coordinates can be accessed by other output commands that use per-atom quantities such as the dump custom command.

IMPORTANT NOTE: To enable displacements to be calculated which include the effects of atoms passing through periodic boundaries, the original coordinates are stored in "unwrapped" form, by using the image flags associated with each atom. See the dump custom command for a discussion of "unwrapped" coordinates. See the Atoms section of the read_data command for a discussion of image flags and how they are set for each atom.

IMPORTANT NOTE: If an atom is part of a rigid body (see the fix rigid command), it's periodic image flags are altered, and its original coordinates may not be what you expect. See the fix rigid command for details.

Restart, fix_modify, output, run start/stop, minimize info:

This fix writes the original coordinates of the atoms to binary restart files, so that the values can be restored when a simulation is restarted. See the read_restart command for info on how to re-specify a fix in an input script that reads a restart file, so that the operation of the fix continues in an uninterrupted fashion.

None of the fix_modify options are relevant to this fix.

This fix produces a per-atom vector which can be accessed by various output commands. The length of the vector for each atom is 3, and the components store the x,y,z coords of each atom. The per-atom values be accessed on any timestep.

No parameter of this fix can be used with the start/stop keywords of the run command. This fix is not invoked during energy minimization.

Restrictions: none

Related commands:

fix msd

Default: none