forked from lijiext/lammps
54 lines
1.7 KiB
Plaintext
54 lines
1.7 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 setforce command :h3
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[Syntax:]
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fix ID group-ID setforce fx fy fz :pre
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ID, group-ID are documented in "fix"_fix.html command
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setforce = style name of this fix command
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fx,fy,fz = force component values :ul
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[Examples:]
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fix freeze indenter setforce 0.0 0.0 0.0
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fix 2 edge setforce NULL 0.0 0.0 :pre
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[Description:]
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Set each component of force on each atom in the group to the specified
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values fx,fy,fz. This erases all previously computed forces on the
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atom, though additional fixes could add new forces. This command can
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be used to freeze certain atoms in the simulation by zeroing their
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force, assuming their initial velocity zero.
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Any of the fx,fy,fz values can be specified as NULL which means do not
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alter the force component in that dimension.
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The forces due to this fix are also imposed during an energy
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minimization, invoked by the "minimize"_minimize.html command.
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The total force on the group of atoms before it is reset is stored by
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the fix and its components can be accessed during thermodynamic
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print-out by using f_ID\[N\] where ID = he fix-ID and N = 1,2,3. See
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the "thermo_style custom"_thermo_style.html command for details. Note
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that the fix stores the total force on the group of atoms, but the
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printed value may be normalized by the total number of atoms in the
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simulation depending on the "thermo_modify norm"_thermo_modify.html
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option you are using.
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[Restrictions:] none
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[Related commands:]
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"fix addforce"_fix_addforce.html, "fix aveforce"_fix_aveforce.html
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[Default:] none
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