2012-02-02 07:34:00 +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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2012-02-04 07:06:57 +08:00
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<H3>pair_style beck command
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2012-02-02 07:34:00 +08:00
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</H3>
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2013-08-23 22:50:59 +08:00
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<H3>pair_style beck/gpu command
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</H3>
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2012-03-02 23:44:23 +08:00
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<H3>pair_style beck/omp command
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</H3>
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2012-02-02 07:34:00 +08:00
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<P><B>Syntax:</B>
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</P>
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2012-02-04 07:06:57 +08:00
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<PRE>pair_style beck Rc
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2012-02-02 07:34:00 +08:00
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</PRE>
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<UL><LI>Rc = cutoff for 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 beck 8.0
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pair_coeff * * 399.671876712 0.0000867636112694 0.675 4.390 0.0003746
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pair_coeff 1 1 399.671876712 0.0000867636112694 0.675 4.390 0.0003746 6.0
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</PRE>
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<P><B>Description:</B>
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</P>
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2012-02-04 07:06:57 +08:00
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<P>Style <I>beck</I> computes interactions based on the potential by
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2012-02-02 07:34:00 +08:00
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<A HREF = "#Beck">(Beck)</A>, originally designed for simulation of Helium. It
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includes truncation at a cutoff distance Rc.
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</P>
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2012-02-02 09:08:48 +08:00
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<CENTER><IMG SRC = "Eqs/pair_beck.jpg">
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2012-02-02 07:34:00 +08:00
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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.
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</P>
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<UL><LI>A (energy units)
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<LI>B (energy-distance^6 units)
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<LI>a (distance units)
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<LI>alpha (1/distance units)
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<LI>beta (1/distance^6 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 cutoff
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Rc is used.
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</P>
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<HR>
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2012-03-02 23:44:23 +08:00
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<P>Styles with a <I>cuda</I>, <I>gpu</I>, <I>omp</I>, or <I>opt</I> suffix are functionally
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the same as the corresponding style without the suffix. They have
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been optimized to run faster, depending on your available hardware, as
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discussed in <A HREF = "Section_accelerate.html">Section_accelerate</A> of the
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manual. The accelerated styles take the same arguments and should
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produce the same results, except for round-off and precision issues.
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</P>
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<P>These accelerated styles are part of the USER-CUDA, GPU, USER-OMP and OPT
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packages, respectively. They are only enabled if LAMMPS was built with
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those packages. See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A>
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section for more info.
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</P>
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<P>You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the <A HREF = "Section_start.html#start_7">-suffix command-line
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switch</A> when you invoke LAMMPS, or you can
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use the <A HREF = "suffix.html">suffix</A> command in your input script.
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</P>
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<P>See <A HREF = "Section_accelerate.html">Section_accelerate</A> of the manual for
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more instructions on how to use the accelerated styles effectively.
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</P>
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<HR>
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2012-02-02 07:34:00 +08:00
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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, coeffiecients must be specified.
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No default miture rules are used.
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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> 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 does not support the <A HREF = "pair_modify.html">pair_modify</A>
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tail option for adding long-range tail corrections.
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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> 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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<HR>
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<A NAME = "Beck"></A>
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<P><B>(Beck)</B> Beck, Molecular Physics, 14, 311 (1968).
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</P>
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</HTML>
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