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lammps/doc/fix_store_coord.txt
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fix_store_coord.txt
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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
:line
fix coord/original command :h3
[Syntax:]
fix ID group-ID coord/original keyword values ... :pre
ID, group-ID are documented in "fix"_fix.html command :ulb,l
coord/original = style name of this fix command :l
zero or more keyword/value pairs may be appended :l
keyword = {com} :l
{com} value = {yes} or {no} :pre
:ule
[Examples:]
fix 1 all coord/original
fix 1 upper coord/original com yes :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.
If the {com} keyword is set to {yes} then the position
of each atom relative to the center-of-mass of the group of
atoms is stored, instead of the absolute position. This option
is used by the "compute msd"_compute_msd.html command.
[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 array which can be accessed by various
"output commands"_Section_howto.html#4_15. The number of columns
for each atom is 3, and the columns 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:]
"compute msd"_compute_msd.html, "compute
displace/atom"_compute_displace_atom.html
[Default:]
The option default is com = no.
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