lammps/doc/fix_setforce.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 setforce command :h3
[Syntax:]
fix ID group-ID setforce fx fy fz :pre
ID, group-ID are documented in "fix"_fix.html command
setforce = style name of this fix command
fx,fy,fz = force component values :ul
[Examples:]
fix freeze indenter setforce 0.0 0.0 0.0
fix 2 edge setforce NULL 0.0 0.0 :pre
[Description:]
Set each component of force on each atom in the group to the specified
values fx,fy,fz. This erases all previously computed forces on the
atom, though additional fixes could add new forces. This command can
be used to freeze certain atoms in the simulation by zeroing their
force, assuming their initial velocity zero.
Any of the fx,fy,fz values can be specified as NULL which means do not
alter the force component in that dimension.
The forces due to this fix are also imposed during an energy
minimization, invoked by the "minimize"_minimize.html command.
[Restrictions:] none
[Related commands:]
"fix addforce"_fix_addforce.html, "fix aveforce"_fix_aveforce.html
[Default:] none