forked from lijiext/lammps
73 lines
2.5 KiB
Plaintext
73 lines
2.5 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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fix coord/original command :h3
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[Syntax:]
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fix ID group-ID coord/original :pre
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ID, group-ID are documented in "fix"_fix.html command
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coord/original = style name of this fix command :ul
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[Examples:]
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fix 1 all coord/original :pre
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[Description:]
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Store the original coordinates of atoms in the group at the time the
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fix command is issued. This is useful for computing a displacement of
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the atoms at later times, via the "compute
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displace/atom"_compute_displace_atom.html command. Or the original
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coordinates can be accessed by other "output
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commands"_Section_howto.html#4_15 that use per-atom quantities such as
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the "dump custom"_dump.html command.
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IMPORTANT NOTE: To enable displacements to be calculated which include
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the effects of atoms passing through periodic boundaries, the original
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coordinates are stored in "unwrapped" form, by using the image flags
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associated with each atom. See the "dump custom"_dump.html command
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for a discussion of "unwrapped" coordinates. See the Atoms section of
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the "read_data"_read_data.html command for a discussion of image flags
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and how they are set for each atom.
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IMPORTANT NOTE: If an atom is part of a rigid body (see the "fix
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rigid"_fix_rigid.html command), it's periodic image flags are altered,
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and its original coordinates may not be what you expect. See the
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"fix rigid"_fix_rigid.html command for details.
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[Restart, fix_modify, output, run start/stop, minimize info:]
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This fix writes the original coordinates of the atoms to "binary
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restart files"_restart.html, so that the values can be restored when a
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simulation is restarted. See the "read_restart"_read_restart.html
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command for info on how to re-specify a fix in an input script that
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reads a restart file, so that the operation of the fix continues in an
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uninterrupted fashion.
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None of the "fix_modify"_fix_modify.html options are relevant to this
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fix.
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This fix produces a per-atom vector which can be accessed by various
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"output commands"_Section_howto.html#4_15. The length of the vector
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for each atom is 3, and the components store the x,y,z coords of each
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atom. The per-atom values be accessed on any timestep.
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No parameter of this fix can be used with the {start/stop} keywords of
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the "run"_run.html command. This fix is not invoked during "energy
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minimization"_minimize.html.
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[Restrictions:] none
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[Related commands:]
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"fix msd"_fix_msd.html
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[Default:] none
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