forked from lijiext/lammps
66 lines
2.2 KiB
Plaintext
66 lines
2.2 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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compute displace/atom command :h3
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[Syntax:]
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compute ID group-ID displace/atom fix-ID :pre
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ID, group-ID are documented in "compute"_compute.html command
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displace/atom = style name of this compute command
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fix-ID = ID of a fix of style "coord/original"_fix_coord_original.html :ul
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[Examples:]
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compute 1 all displace/atom myCoords :pre
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[Description:]
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Define a computation that calculates the current displacement of each
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atom in the group from its original coordinates, including all effects
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due to atoms passing thru periodic boundaries. The original
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coordinates are stored by a "fix
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coord/original"_fix_coord_original.html command, whose ID must be
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specified with this compute. They are the coordinates at the time the
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fix command was issued.
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IMPORTANT NOTE: The fix coord/original command stores the initial
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coordinates in "unwrapped" form, by using the image flags associated
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with each atom. See the "dump custom"_dump.html command for a
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discussion of "unwrapped" coordinates. See the Atoms section of the
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"read_data"_read_data.html command for a discussion of image flags and
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how they are set for each atom. You can reset the image flags
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(e.g. to 0) before invoking the fix and this compute by using the "set
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image"_set.html command.
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The displacements can be output directly via the "dump
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custom"_dump.html command.
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The value of the displacement will be 0.0 for atoms not in the
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specified compute group. Note that the fix defines its own group and
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stores (0.0,0.0,0.0) for the original coordinates of any atom not in
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the fix group.
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[Output info:]
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This compute calculates a vector of length 4 for each atom, which can
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be accessed by indices 1-4 by any command that uses per-atom computes
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as input. See "this section"_Section_howto.html#4_15 for an overview
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of LAMMPS output options. The first 3 components of the vector are
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the x,y,z displacements. The 4th component is the total displacement,
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i.e. sqrt(dx*dx + dy*dy + dz*dz).
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[Restrictions:] none
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[Related commands:]
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"dump custom"_dump.html, "fix msd"_fix_msd.html
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[Default:] none
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