forked from lijiext/lammps
88 lines
2.7 KiB
HTML
88 lines
2.7 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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</CENTER>
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<HR>
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<H3>bond_style class2 command
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</H3>
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<H3>bond_style class2/omp command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>bond_style class2
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</PRE>
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<P><B>Examples:</B>
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</P>
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<PRE>bond_style class2
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bond_coeff 1 1.0 100.0 80.0 80.0
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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>class2</I> bond style uses the potential
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</P>
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<CENTER><IMG SRC = "Eqs/bond_class2.jpg">
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</CENTER>
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<P>where r0 is the equilibrium bond distance.
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</P>
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<P>See <A HREF = "#Sun">(Sun)</A> for a description of the COMPASS class2 force field.
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</P>
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<P>The following coefficients must be defined for each bond type via the
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<A HREF = "bond_coeff.html">bond_coeff</A> command as in the example above, or in
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the data file or restart files read by the <A HREF = "read_data.html">read_data</A>
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or <A HREF = "read_restart.html">read_restart</A> commands:
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</P>
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<UL><LI>R0 (distance)
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<LI>K2 (energy/distance^2)
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<LI>K3 (energy/distance^3)
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<LI>K4 (energy/distance^4)
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</UL>
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<HR>
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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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<P><B>Restrictions:</B>
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</P>
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<P>This bond style can only be used if LAMMPS was built with the CLASS2
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package. See the <A HREF = "Section_start.html#start_3">Making LAMMPS</A> section
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for more info on packages.
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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 = "bond_coeff.html">bond_coeff</A>, <A HREF = "delete_bonds.html">delete_bonds</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 = "Sun"></A>
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<P><B>(Sun)</B> Sun, J Phys Chem B 102, 7338-7364 (1998).
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</P>
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</HTML>
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