forked from lijiext/lammps
119 lines
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HTML
119 lines
4.0 KiB
HTML
<HTML>
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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 lj96/cut command
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</H3>
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<H3>pair_style lj96/cut/gpu 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 style cutoff
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</PRE>
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<UL><LI>style = <I>lj96/cut</I> or <I>lj96/cut/gpu</I>
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<LI>cutoff = global cutoff for lj96/cut 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 lj96/cut 2.5
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pair_style lj96/cut/gpu 2.5
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pair_coeff * * 1.0 1.0 4.0
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pair_coeff 1 1 1.0 1.0
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>The <I>lj96/cut</I> style compute a 9/6 Lennard-Jones potential, instead
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of the standard 12/6 potential, given by
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</P>
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<CENTER><IMG SRC = "Eqs/pair_lj96.jpg">
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</CENTER>
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<P>Rc is the cutoff.
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</P>
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<P>Style <I>lj96/cut/gpu</I> is a GPU-enabled version of style <I>lj96/cut</I>.
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See more details below.
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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, 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 LJ
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cutoff specified in the pair_style command is used.
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</P>
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<HR>
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<P>The <I>lj96/cut/gpu</I> style is identical to the <I>lj96/cut</I> style, except that
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each processor off-loads its pairwise calculations to a
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GPU chip. Depending on the hardware available on your system this can provide a
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speed-up. See the <A HREF = "Section_start.html#2_8">Running on GPUs</A> section of
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the manual for more details about hardware and software requirements
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for using GPUs.
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</P>
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<P>More details about these settings and various possible hardware
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configuration are in <A HREF = "Section_start.html#2_8">this section</A> of the
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manual.
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</P>
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<P>Additional requirements in your input script to run with the <I>lj96/cut/gpu</I>
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style are as follows:
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</P>
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<P>The <A HREF = "newton.html">newton pair</A> setting must be <I>off</I> and
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<A HREF = "fix_gpu.html">fix gpu</A> must be used. The fix controls the
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essential GPU selection and initialization steps
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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 coefficients
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and cutoff distance for all of the lj/cut pair styles can be mixed.
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The default mix value is <I>geometric</I>. See the "pair_modify" command
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for details.
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</P>
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<P>This pair style supports the <A HREF = "pair_modify.html">pair_modify</A> shift
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option for the energy of the pair interaction.
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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 supports the <A HREF = "pair_modify.html">pair_modify</A> tail
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option for adding a long-range tail correction to the energy and
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pressure of the pair interaction.
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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 supports the use of the <I>inner</I>, <I>middle</I>, and <I>outer</I>
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keywords of the <A HREF = "run_style.html">run_style respa</A> command, meaning the
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pairwise forces can be partitioned by distance at different levels of
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the rRESPA hierarchy. See the <A HREF = "run_style.html">run_style</A> command for
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details.
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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>The <I>lj96/cut/gpu</I> style is part of the "gpu" package. It
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is only enabled if LAMMPS is built with this packages. See the
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<A HREF = "Section_start.html#2_3">Making 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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</HTML>
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