lammps/doc/fix_coord_original.txt

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fix coord/original command :h3

[Syntax:]

fix ID group-ID coord/original :pre

ID, group-ID are documented in "fix"_fix.html command
coord/original = style name of this fix command :ul

[Examples:]

fix 1 all coord/original :pre

[Description:]

Store the original coordinates of atoms in the group at the time the
fix command is issued.  This is used for computing a displacement of
the atoms at later times, via the "compute
displace/atom"_compute_displace_atom.html command.  Or the original
coordinates can be accessed by other "output
commands"_Section_howto.html#4_15 that use per-atom quantities such as
the "dump custom"_dump.html command.

IMPORTANT NOTE: The original coordinates are stored in "unwrapped"
form, by using the image flags associated with each atom.  See the
"dump custom"_dump.html command for a discussion of "unwrapped"
coordinates.  See the Atoms section of the "read_data"_read_data.html
command for a discussion of image flags and how they are set for each
atom.  You can reset the image flags (e.g. to 0) before invoking this
fix by using the "set image"_set.html command.

IMPORTANT NOTE: If an atom is part of a rigid body (see the "fix
rigid"_fix_rigid.html command), it's periodic image flags are altered,
and its original coordinates may not be what you expect.  See the
"fix rigid"_fix_rigid.html 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"_restart.html, so that the values can be restored when a
simulation is restarted.  See the "read_restart"_read_restart.html
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"_fix_modify.html options are relevant to this
fix.

This fix produces a per-atom vector which can be accessed by various
"output commands"_Section_howto.html#4_15.  The length of the vector
for each atom is 3, and the components store the original unwrapped
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"_run.html command.  This fix is not invoked during "energy
minimization"_minimize.html.

[Restrictions:] none

[Related commands:]

"fix msd"_fix_msd.html, "compute
displace/atom"_compute_displace_atom.html

[Default:] none