Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F93210285
improper_umbrella.html
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Wed, Nov 27, 01:17
Size
3 KB
Mime Type
text/html
Expires
Fri, Nov 29, 01:17 (2 d)
Engine
blob
Format
Raw Data
Handle
22596343
Attached To
rLAMMPS lammps
improper_umbrella.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>improper_style umbrella command
</H3>
<H3>improper_style umbrella/omp command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>improper_style umbrella
</PRE>
<P><B>Examples:</B>
</P>
<PRE>improper_style umbrella
improper_coeff 1 100.0 180.0
</PRE>
<P><B>Description:</B>
</P>
<P>The <I>umbrella</I> improper style uses the following potential, which is
commonly referred to as a classic inversion and used in the
<A HREF = "Section_howto.html#howto_4">DREIDING</A> force field:
</P>
<CENTER><IMG SRC = "Eqs/improper_umbrella.jpg">
</CENTER>
<P>where K is the force constant and omega is the angle between the IL
axis and the IJK plane:
</P>
<CENTER><IMG SRC = "Eqs/umbrella.jpg">
</CENTER>
<P>If omega0 = 0 the potential term has a minimum for the planar
structure. Otherwise it has two minima at +/- omega0, with a barrier
in between.
</P>
<P>See <A HREF = "#Mayo">(Mayo)</A> for a description of the DREIDING force field.
</P>
<P>The following coefficients must be defined for each improper type via
the <A HREF = "improper_coeff.html">improper_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>K (energy)
<LI>omega0 (degrees)
</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 improper style can only be used if LAMMPS was built with the
MOLECULAR 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 = "improper_coeff.html">improper_coeff</A>
</P>
<P><B>Default:</B> none
</P>
<HR>
<A NAME = "Mayo"></A>
<P><B>(Mayo)</B> Mayo, Olfason, Goddard III, J Phys Chem, 94, 8897-8909
(1990),
</P>
</HTML>
Event Timeline
Log In to Comment