2009-12-22 08:34:36 +08:00
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"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 store/force command :h3
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[Syntax:]
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fix ID group-ID store/force :pre
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ID, group-ID are documented in "fix"_fix.html command
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store/force = style name of this fix command :ul
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[Examples:]
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fix 1 all store/force :pre
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[Description:]
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2010-06-04 08:14:14 +08:00
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Store the forces on atoms in the group at the point during each
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timestep when the fix is invoked, as described below. This is useful
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for storing forces before constraints or other boundary conditions are
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computed which modify the forces, so that unmodified forces can be
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"written to a dump file"_dump.html or accessed by other "output
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commands"_Section_howto.html#4_15 that use per-atom quantities.
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2009-12-22 08:34:36 +08:00
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This fix is invoked at the point in the velocity-Verlet timestepping
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immediately after "pair"_pair_style.html, "bond"_bond_style.html,
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"angle"_angle_style.html, "dihedral"_dihedral_style.html,
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"improper"_improper_style.html, and "long-range"_kspace_style.html
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forces have been calculated. It is the point in the timestep when
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various fixes that compute constraint forces are calculated and
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potentially modify the force on each atom. Examples of such fixes are
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"fix shake"_fix_shake.html, "fix wall"_fix_wall.html, and "fix
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indent"_fix_indent.html.
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IMPORTANT NOTE: The order in which various fixes are applied which
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operate at the same point during the timestep, is the same as the
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order they are specified in the input script. Thus normally, if you
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want to store per-atom forces due to force field interactions, before
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constraints are applied, you should list this fix first within that
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set of fixes, i.e. before other fixes that apply constraints.
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However, if you wish to include certain constraints (e.g. fix shake)
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in the stored force, then it could be specified after some fixes and
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before others.
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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.
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This fix produces a per-atom array which can be accessed by various
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"output commands"_Section_howto.html#4_15. The number of columns for
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each atom is 3, and the columns store the x,y,z forces on each atom.
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The per-atom values be accessed on any timestep.
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No parameter of this fix can be used with the {start/stop} keywords of
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the "run"_run.html command. This fix is not invoked during "energy
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minimization"_minimize.html.
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[Restrictions:] none
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[Related commands:]
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2010-06-04 08:37:28 +08:00
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"fix store_state"_fix_store_state.html
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2009-12-22 08:34:36 +08:00
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[Default:] none
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