forked from lijiext/lammps
60 lines
2.0 KiB
Plaintext
60 lines
2.0 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 wiggle command :h3
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[Syntax:]
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fix ID group-ID wiggle dim amplitude period
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ID, group-ID are documented in "fix"_fix.html command
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wiggle = style name of this fix command
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dim = {x} or {y} or {z}
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amplitude = size of oscillation (distance units)
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period = time of oscillation (time units) :ul
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[Examples:]
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fix 1 frozen wiggle y 3.0 0.5 :pre
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[Description:]
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Move a group of atoms in a sinusoidal oscillation. This is useful in
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granular simulations when boundary atoms are wiggled to induce packing
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of the dynamic atoms. The dimension {dim} of movement is specified as
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is the {amplitude} and {period} of the oscillations. Each timestep
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the {dim} coordinate of each atom is set to
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coord = coord0 + A - A cos (omega * delta) :pre
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where {coord0} is the coordinate at the time the fix was specified,
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{A} is the {amplitude}, {omega} is 2 PI / {period}, and {delta} is the
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elapsed time since the fix was specified. The velocity of the atom is
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set to the derivative of this expression.
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Note that if a value of A > 0 is specified, each wiggling atom does
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not oscillate around its initial position, but moves entirely in the
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positive direction relative to its initial position. This is so that
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its initial velocity will be 0.0.
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[Restart, fix_modify, output, run start/stop, minimize info:]
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No information about this fix is written to "binary restart
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files"_restart.html. None of the "fix_modify"_fix_modify.html options
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are relevant to this fix. No global scalar or vector or per-atom
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quantities are stored by this fix for access by various "output
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commands"_Section_howto.html#4_15. No parameter of this fix can be
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used with the {start/stop} keywords of the "run"_run.html command.
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This fix is not invoked during "energy minimization"_minimize.html.
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[Restrictions:] none
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[Related commands:] none
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[Default:] none
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