"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)

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fix manifoldforce command :h3

[Syntax:]

fix ID group-ID manifoldforce manifold manifold-args ... :pre

ID, group-ID are documented in "fix"_fix.html command :ulb,l
manifold = name of the manifold :l
manifold-args = parameters for the manifold :l

:ule

[Examples:]

fix constrain all manifoldforce sphere 5.0

[Description:]

This fix subtracts each time step from the force the component along the normal of the specified "manifold"_manifolds.html.
This can be used in combination with "minimize"_minimize.html to remove overlap between particles while
keeping them (roughly) constrained to the given manifold, e.g. to set up a run with "fix nve/manifold/rattle"_fix_nve_manifold_rattle.html.
I have found that only {hftn} and {quickmin} with a very small time step perform adequately though.

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[Restart, fix_modify, output, run start/stop, minimize info:]

No information about this fix is written to "binary restart
files"_restart.html.  None of the "fix_modify"_fix_modify.html options
are relevant to this fix.  No global or per-atom quantities are stored
by this fix for access by various "output
commands"_Section_howto.html#howto_15.  No parameter of this fix can
be used with the {start/stop} keywords of the "run"_run.html command.
This fix is invoked during "energy minimization"_minimize.html.

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[Restrictions:]

This fix is part of the USER-MANIFOLD package. It is only enabled if LAMMPS
was built with that package. See the "Making LAMMPS"_Section_start.html#start_3
section for more info.

Only use this with {min_style hftn} or {min_style quickmin}. If not, the constraints
will not be satisfied very well at all. A warning is generated if the {min_style} is
incompatible but no error.

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[Related commands:]

"fix nve/manifold/rattle"_fix_nve_manifold_rattle.html, "fix nvt/manifold/rattle"_fix_nvt_manifold_rattle.html

