forked from lijiext/lammps
89 lines
3.0 KiB
Plaintext
89 lines
3.0 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,Commands_all.html)
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:line
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fix freeze command :h3
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fix freeze/kk command :h3
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[Syntax:]
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fix ID group-ID freeze :pre
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ID, group-ID are documented in "fix"_fix.html command
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freeze = style name of this fix command :ul
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[Examples:]
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fix 2 bottom freeze :pre
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[Description:]
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Zero out the force and torque on a granular particle. This is useful
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for preventing certain particles from moving in a simulation. The
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"granular pair styles"_pair_gran.html also detect if this fix has been
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defined and compute interactions between frozen and non-frozen
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particles appropriately, as if the frozen particle has infinite mass.
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A similar functionality for normal (point) particles can be obtained
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using "fix setforce"_fix_setforce.html.
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:line
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Styles with a {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed on the "Speed packages"_Speed_packages.html doc
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page. The accelerated styles take the same arguments and should
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produce the same results, except for round-off and precision issues.
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These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
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USER-OMP and OPT packages, respectively. They are only enabled if
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LAMMPS was built with those packages. See the "Build
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package"_Build_package.html doc page for more info.
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You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the "-suffix command-line
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switch"_Run_options.html when you invoke LAMMPS, or you can use the
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"suffix"_suffix.html command in your input script.
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See the "Speed packages"_Speed_packages.html doc page for more
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instructions on how to use the accelerated styles effectively.
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:line
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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 computes a global 3-vector of forces, which can be accessed
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by various "output commands"_Howto_output.html. This is the total
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force on the group of atoms before the forces on individual atoms are
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changed by the fix. The vector values calculated by this fix are
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"extensive".
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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:]
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This fix is part of the GRANULAR package. It is only enabled if
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LAMMPS was built with that package. See the "Build
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package"_Build_package.html doc page for more info.
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There can only be a single freeze fix defined. This is because other
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the "granular pair styles"_pair_gran.html treat frozen particles
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differently and need to be able to reference a single group to which
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this fix is applied.
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[Related commands:]
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"atom_style sphere"_atom_style.html, "fix setforce"_fix_setforce.html
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[Default:] none
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