2011-08-09 07:15:07 +08:00
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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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<HR>
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<H3>pair_style lj/sf 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/sf cutoff
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</PRE>
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<UL><LI>cutoff = global cutoff for Lennard-Jones 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/sf 2.5
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pair_coeff * * 1.0 1.0
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pair_coeff 1 1 1.0 1.0 3.0
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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/sf</I> computes a truncated and force-shifted LJ interaction
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(Shifted Force Lennard-Jones), so that both the potential and the
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force go continuously to zero at the cutoff <A HREF = "#Toxvaerd">(Toxvaerd)</A>:
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</P>
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<CENTER><IMG SRC = "Eqs/pair_lj_sf.jpg">
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</CENTER>
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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, or by mixing as described below:
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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>cutoff (distance units)
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</UL>
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<P>The last coefficient is optional. If not specified, the global
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LJ cutoff specified in the pair_style command is used.
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</P>
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<HR>
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<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
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</P>
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<P>For atom type pairs I,J and I != J, the epsilon and sigma
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coefficients and 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
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default mix value is <I>geometric</I>. See the "pair_modify" command for
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details.
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</P>
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<P>The <A HREF = "pair_modify.html">pair_modify</A> shift option is not relevant for
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this pair style, since the pair interaction goes to 0.0 at the cutoff.
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</P>
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<P>The <A HREF = "pair_modify.html">pair_modify</A> table option is not relevant
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for this pair style.
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</P>
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<P>This pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
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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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</P>
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<P>This pair style writes its information to <A HREF = "restart.html">binary restart
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files</A>, 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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</P>
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<P>This pair style can only be used via the <I>pair</I> keyword of the
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<A HREF = "run_style.html">run_style respa</A> command. It does not support the
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<I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
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</P>
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<HR>
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<P><B>Restrictions:</B>
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</P>
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<P>This pair style is part of the "user-misc" package. It is only
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2011-08-26 00:46:23 +08:00
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enabled if LAMMPS was built with that package. See the <A HREF = "Section_start.html#start_3">Making
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2011-08-09 07:15:07 +08:00
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LAMMPS</A> section for more info.
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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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<HR>
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<A NAME = "Toxvaerd"></A>
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<P><B>(Toxvaerd)</B> Toxvaerd, Dyre, J Chem Phys, 134, 081102 (2011).
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</P>
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</HTML>
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