forked from lijiext/lammps
124 lines
4.3 KiB
Plaintext
124 lines
4.3 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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pair_style lj/smooth command :h3
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pair_style lj/smooth/cuda command :h3
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pair_style lj/smooth/omp command :h3
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[Syntax:]
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pair_style lj/smooth Rin Rc :pre
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Rin = inner cutoff beyond which force smoothing will be applied (distance units)
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Rc = outer cutoff for lj/smooth interactions (distance units) :ul
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[Examples:]
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pair_style lj/smooth 8.0 10.0
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pair_coeff * * 10.0 1.5
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pair_coeff 1 1 20.0 1.3 7.0 9.0 :pre
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[Description:]
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Style {lj/smooth} computes a LJ interaction with a force smoothing
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applied between the inner and outer cutoff.
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:c,image(Eqs/pair_lj_smooth.jpg)
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The polynomial coefficients C1, C2, C3, C4 are computed by LAMMPS to
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cause the force to vary smoothly from the inner cutoff Rin to the
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outer cutoff Rc.
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At the inner cutoff the force and its 1st derivative
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will match the unsmoothed LJ formula. At the outer cutoff the force
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and its 1st derivative will be 0.0. The inner cutoff cannot be 0.0.
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NOTE: this force smoothing causes the energy to be discontinuous both
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in its values and 1st derivative. This can lead to poor energy
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conservation and may require the use of a thermostat. Plot the energy
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and force resulting from this formula via the
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"pair_write"_pair_write.html command to see the effect.
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The following coefficients must be defined for each pair of atoms
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types via the "pair_coeff"_pair_coeff.html command as in the examples
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above, or in the data file or restart files read by the
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"read_data"_read_data.html or "read_restart"_read_restart.html
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commands, or by mixing as described below:
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epsilon (energy units)
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sigma (distance units)
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innner (distance units)
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outer (distance units) :ul
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The last 2 coefficients are optional inner and outer cutoffs. If not
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specified, the global values for Rin and Rc are used.
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:line
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Styles with a {cuda}, {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 in "Section_accelerate"_Section_accelerate.html
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of the manual. The accelerated styles take the same arguments and
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should produce the same results, except for round-off and precision
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issues.
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These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
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KOKKOS, USER-OMP and OPT packages, respectively. They are only
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enabled if LAMMPS was built with those packages. See the "Making
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LAMMPS"_Section_start.html#start_3 section 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"_Section_start.html#start_7 when you invoke LAMMPS, or you can
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use the "suffix"_suffix.html command in your input script.
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See "Section_accelerate"_Section_accelerate.html of the manual for
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more instructions on how to use the accelerated styles effectively.
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:line
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[Mixing, shift, table, tail correction, restart, rRESPA info]:
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For atom type pairs I,J and I != J, the epsilon, sigma, Rin
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coefficients and the cutoff distance for this pair style can be mixed.
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Rin is a cutoff value and is mixed like the cutoff. The other
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coefficients are mixed according to the pair_modify mix option. The
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default mix value is {geometric}. See the "pair_modify" command for
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details.
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This pair style supports the "pair_modify"_pair_modify.html shift
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option for the energy of the pair interaction.
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The "pair_modify"_pair_modify.html table option is not relevant
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for this pair style.
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This pair style does not support the "pair_modify"_pair_modify.html
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tail option for adding long-range tail corrections to energy and
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pressure, since the energy of the pair interaction is smoothed to 0.0
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at the cutoff.
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This pair style writes its information to "binary restart
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files"_restart.html, so pair_style and pair_coeff commands do not need
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to be specified in an input script that reads a restart file.
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This pair style can only be used via the {pair} keyword of the
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"run_style respa"_run_style.html command. It does not support the
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{inner}, {middle}, {outer} keywords.
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:line
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[Restrictions:] none
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[Related commands:]
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"pair_coeff"_pair_coeff.html, "pair
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lj/smooth/linear"_pair_lj_smooth_linear.html
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[Default:] none
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