2006-09-22 00:22:34 +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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pair_style lj/expand command :h3
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[Syntax:]
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pair_style lj/expand cutoff :pre
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cutoff = global cutoff for lj/expand interactions (distance units) :ul
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[Examples:]
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pair_style lj/expand 2.5
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pair_coeff * * 1.0 1.0 0.5
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pair_coeff 1 1 1.0 1.0 -0.2 2.0 :pre
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[Description:]
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Style {lj/expand} computes a LJ interaction with a distance shifted by
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delta which can be useful when particles are of different sizes, since
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it is different that using different sigma values in a standard LJ
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formula:
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:c,image(Eqs/pair_lj_expand.jpg)
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Rc is the cutoff which does not include the delta distance. I.e. the
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actual force cutoff is the sum of cutoff + delta.
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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:
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epsilon (energy units)
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sigma (distance units)
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delta (distance units)
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cutoff (distance units) :ul
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The delta values can be positive or negative. The last coefficient is
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optional. If not specified, the global LJ cutoff is used.
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2007-04-20 07:25:27 +08:00
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If the pair_coeff command is not used to define coefficients for a
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particular I != J type pair, the mixing rule is set by the
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"pair_modify"_pair_modify.html command. Additionally, the delta
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coefficient is always mixed by the rule
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delta_ij = (delta_i + delta_j) / 2 :pre
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2006-09-22 00:22:34 +08:00
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[Restrictions:] none
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[Related commands:]
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"pair_coeff"_pair_coeff.html
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[Default:] none
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