2011-08-28 04:09:27 +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 sph/lj 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 sph/lj
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</PRE>
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<P><B>Examples:</B>
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</P>
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<PRE>pair_style sph/lj
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pair_coeff * * 1.0 2.4
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>The sph/lj style computes pressure forces between particles according
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to the Lennard-Jones equation of state, which is computed according to
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Ree's 1980 polynomial fit <A HREF = "#Ree">(Ree)</A>. The Lennard-Jones parameters
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epsilon and sigma are set to unity. This pair style also computes
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Monaghan's artificial viscosity to prevent particles from
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interpentrating <A HREF = "#Monoghan">(Monaghan)</A>.
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</P>
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<P>See <A HREF = "USER/sph/SPH_LAMMPS_userguide.pdf">this PDF guide</A> to using SPH in
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LAMMPS.
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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.
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</P>
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<UL><LI>nu artificial viscosity (no units)
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<LI>h kernel function cutoff (distance units)
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</UL>
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2011-08-28 04:09:27 +08:00
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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>This style does not support mixing. Thus, coefficients for all
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I,J pairs must be specified explicitly.
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</P>
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<P>This style does not support the <A HREF = "pair_modify.html">pair_modify</A>
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shift, table, and tail options.
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</P>
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<P>This style does not write information to <A HREF = "restart.html">binary restart
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files</A>. Thus, you need to re-specify the pair_style and
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pair_coeff commands in an input script that reads a restart file.
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</P>
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<P>This style can only be used via the <I>pair</I> keyword of the <A HREF = "run_style.html">run_style
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respa</A> command. It does not support the <I>inner</I>,
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<I>middle</I>, <I>outer</I> keywords.
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</P>
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<P><B>Restrictions:</B>
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</P>
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<P>As noted above, the Lennard-Jones parameters epsilon and sigma are set
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to unity.
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</P>
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<P>This pair style is part of the USER-SPH package. It is only enabled
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if LAMMPS was built with that package. See the <A HREF = "Section_start.html#start_3">Making
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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>, pair_sph/rhosum
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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 = "Ree"></A>
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<P><B>(Ree)</B> Ree, Journal of Chemical Physics, 73, 5401 (1980).
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</P>
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<A NAME = "Monoghan"></A>
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<P><B>(Monaghan)</B> Monaghan and Gingold, Journal of Computational Physics,
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52, 374-389 (1983).
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</P>
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</HTML>
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