Homec4science
Diffusion lammps (lammm-master-deprecated) Browse

lammps/doc/doc2/dihedral_opls.html
fbfd916c6998lammm-master-deprecated

Last Change
Raw File

dihedral_opls.html
View Options

<HTML>
<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>
</CENTER>
<HR>
<H3>dihedral_style opls command
</H3>
<H3>dihedral_style opls/kk command
</H3>
<H3>dihedral_style opls/omp command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>dihedral_style opls
</PRE>
<P><B>Examples:</B>
</P>
<PRE>dihedral_style opls
dihedral_coeff 1 1.740 -0.157 0.279 0.00 # CT-CT-CT-CT
dihedral_coeff 2 0.000 0.000 0.366 0.000 # CT-CT-CT-HC
dihedral_coeff 3 0.000 0.000 0.318 0.000 # HC-CT-CT-HC
</PRE>
<P><B>Description:</B>
</P>
<P>The <I>opls</I> dihedral style uses the potential
</P>
<CENTER><IMG SRC = "Eqs/dihedral_opls.jpg">
</CENTER>
<P>Note that the usual 1/2 factor is not included in the K values.
</P>
<P>This dihedral potential is used in the OPLS force field and is
described in <A HREF = "#Watkins">(Watkins)</A>.
</P>
<P>The following coefficients must be defined for each dihedral type via the
<A HREF = "dihedral_coeff.html">dihedral_coeff</A> command as in the example above, or in
the data file or restart files read by the <A HREF = "read_data.html">read_data</A>
or <A HREF = "read_restart.html">read_restart</A> commands:
</P>
<UL><LI>K1 (energy)
<LI>K2 (energy)
<LI>K3 (energy)
<LI>K4 (energy)
</UL>
<HR>
<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
functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available
hardware, as discussed in <A HREF = "Section_accelerate.html">Section_accelerate</A>
of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
issues.
</P>
<P>These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
KOKKOS, USER-OMP and OPT packages, respectively. They are only
enabled if LAMMPS was built with those packages. See the <A HREF = "Section_start.html#start_3">Making
LAMMPS</A> section for more info.
</P>
<P>You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the <A HREF = "Section_start.html#start_7">-suffix command-line
switch</A> when you invoke LAMMPS, or you can
use the <A HREF = "suffix.html">suffix</A> command in your input script.
</P>
<P>See <A HREF = "Section_accelerate.html">Section_accelerate</A> of the manual for
more instructions on how to use the accelerated styles effectively.
</P>
<HR>
<P><B>Restrictions:</B>
</P>
<P>This dihedral style can only be used if LAMMPS was built with the
MOLECULE package (which it is by default). See the <A HREF = "Section_start.html#start_3">Making
LAMMPS</A> section for more info on packages.
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "dihedral_coeff.html">dihedral_coeff</A>
</P>
<P><B>Default:</B> none
</P>
<HR>
<A NAME = "Watkins"></A>
<P><B>(Watkins)</B> Watkins and Jorgensen, J Phys Chem A, 105, 4118-4125 (2001).
</P>
</HTML>
c4science · Help