2006-09-22 00:22:34 +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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<H3>bond_style fene command
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</H3>
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2011-12-01 23:35:32 +08:00
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<H3>bond_style fene/omp command
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</H3>
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2006-09-22 00:22:34 +08:00
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<P><B>Syntax:</B>
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</P>
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<PRE>bond_style fene
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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 fene
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bond_coeff 1 30.0 1.5 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>fene</I> bond style uses the potential
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</P>
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<CENTER><IMG SRC = "Eqs/bond_fene.jpg">
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</CENTER>
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<P>to define a finite extensible nonlinear elastic (FENE) potential
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<A HREF = "#Kremer">(Kremer)</A>, used for bead-spring polymer models. The first
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term is attractive, the 2nd Lennard-Jones term is repulsive. The
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first term extends to R0, the maximum extent of the bond. The 2nd
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term is cutoff at 2^(1/6) sigma, the minimum of the LJ potential.
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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>K (energy/distance^2)
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<LI>R0 (distance)
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<LI>epsilon (energy)
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<LI>sigma (distance)
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</UL>
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2011-12-01 23:35:32 +08:00
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<HR>
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2014-08-15 00:30:25 +08:00
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<P>Styles with a <I>cuda</I>, <I>gpu</I>, <I>intel</I>, <I>kk</I>, <I>omp</I>, or <I>opt</I> suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed in <A HREF = "Section_accelerate.html">Section_accelerate</A>
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of the manual. The accelerated styles take the same arguments and
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should produce the same results, except for round-off and precision
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issues.
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</P>
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<P>These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
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KOKKOS, USER-OMP and OPT packages, respectively. They are only
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enabled if LAMMPS was built with those packages. See the <A HREF = "Section_start.html#start_3">Making
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LAMMPS</A> section for more info.
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2011-12-01 23:35:32 +08:00
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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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2012-01-28 07:39:14 +08:00
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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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2011-12-01 23:35:32 +08:00
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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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2011-12-14 04:35:35 +08:00
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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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2011-12-01 23:35:32 +08:00
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</P>
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<HR>
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2007-06-25 22:36:36 +08:00
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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
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2015-02-26 05:42:32 +08:00
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MOLECULE package (which it is by default). See the <A HREF = "Section_start.html#start_3">Making
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2007-06-25 22:36:36 +08:00
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LAMMPS</A> section for more info on packages.
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2006-09-22 00:22:34 +08:00
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</P>
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2009-01-14 22:29:55 +08:00
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<P>You typically should specify <A HREF = "special_bonds.html"">special_bonds fene</A>
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or <A HREF = "special_bonds.html">special_bonds lj/coul 0 1 1</A> to use this bond
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style. LAMMPS will issue a warning it that's not the case.
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2008-07-30 03:56:08 +08:00
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</P>
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2006-09-22 00:22:34 +08:00
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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 = "Kremer"></A>
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<P><B>(Kremer)</B> Kremer, Grest, J Chem Phys, 92, 5057 (1990).
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</P>
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</HTML>
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