forked from lijiext/lammps
61 lines
1.6 KiB
HTML
61 lines
1.6 KiB
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<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
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</CENTER>
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<HR>
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<H3>pair_style lj/expand command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>pair_style lj/expand cutoff
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</PRE>
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<UL><LI>cutoff = global cutoff for lj/expand interactions (distance units)
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>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
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Style <I>lj/expand</I> 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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</P>
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<CENTER><IMG SRC = "Eqs/pair_lj_expand.jpg">
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</CENTER>
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<P>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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</P>
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<P>The following coefficients must be defined for each pair of atoms
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types via the <A HREF = "pair_coeff.html">pair_coeff</A> 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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<A HREF = "read_data.html">read_data</A> or <A HREF = "read_restart.html">read_restart</A>
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commands:
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</P>
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<UL><LI>epsilon (energy units)
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<LI>sigma (distance units)
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<LI>delta (distance units)
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<LI>cutoff (distance units)
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</UL>
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<P>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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</P>
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<P><B>Restrictions:</B> none
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "pair_coeff.html">pair_coeff</A>
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</P>
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<P><B>Default:</B> none
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</P>
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</HTML>
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