2010-10-08 05:20:45 +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 gauss command
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</H3>
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2011-10-07 01:32:51 +08:00
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<H3>pair_style gauss/omp command
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</H3>
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2010-10-08 05:20:45 +08:00
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<P><B>Syntax:</B>
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</P>
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<PRE>pair_style gauss cutoff
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</PRE>
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<UL><LI>cutoff = global cutoff for Gauss 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 gauss 12.0
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pair_coeff * * 1.0 0.9
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pair_coeff 1 4 1.0 0.9 10.0
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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>gauss</I> computes a tethering potential of the form
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</P>
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<CENTER><IMG SRC = "Eqs/pair_gauss.jpg">
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</CENTER>
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<P>between an atom and its corresponding tether site which will typically
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be a frozen atom in the simulation. Rc is the cutoff.
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</P>
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<P>The following coefficients must be defined for each pair of atom types
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via the <A HREF = "pair_coeff.html">pair_coeff</A> command as in the examples above,
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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 (1/distance^2 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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is used.
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</P>
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<HR>
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2011-10-07 01:32:51 +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,
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as discussed in <A HREF = "Section_accelerate.html">this section</A> of the manual.
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The accelerated styles take the same arguments and should produce the
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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_6">-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">this section</A> of the manual for more
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instructions on how to use the accelerated styles effectively.
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</P>
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<HR>
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2010-10-08 05:20:45 +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>This pair 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 pair style does not support the <A HREF = "pair_modify.html">pair_modify</A>
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shift option. There is no effect due to the Gaussian well beyond the
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cutoff; hence reasonable cutoffs need to be specified.
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</P>
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<P>The <A HREF = "pair_modify.html">pair_modify</A> table and tail options are not
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relevant 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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table option, since a tabulation capability does not exist for this
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potential.
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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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2010-10-23 05:24:33 +08:00
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<P>This pair style tallies an "occupancy" count of how many Gaussian-well
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sites have an atom within the distance at which the force is a maximum
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= sqrt(0.5/b). This quantity can be accessed via the <A HREF = "compute_pair.html">compute
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pair</A> command as a vector of values of length 1.
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</P>
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<P>To print this quantity to the log file (with a descriptive column
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heading) the following commands could be included in an input script:
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</P>
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<PRE>compute gauss all pair gauss
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variable occ equal c_gauss[1]
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thermo_style custom step temp epair v_occ
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</PRE>
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2010-10-08 05:20:45 +08:00
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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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2010-10-23 05:24:33 +08:00
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<P><A HREF = "pair_coeff.html">pair_coeff</A>
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2010-10-08 05:20:45 +08:00
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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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