forked from lijiext/lammps
63 lines
1.9 KiB
HTML
63 lines
1.9 KiB
HTML
<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>compute com command
|
|
</H3>
|
|
<P><B>Syntax:</B>
|
|
</P>
|
|
<PRE>compute ID group-ID com
|
|
</PRE>
|
|
<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
|
|
<LI>com = style name of this compute command
|
|
</UL>
|
|
<P><B>Examples:</B>
|
|
</P>
|
|
<PRE>compute 1 all com
|
|
</PRE>
|
|
<P><B>Description:</B>
|
|
</P>
|
|
<P>Define a computation that calculates the center-of-mass of the group
|
|
of atoms, including all effects due to atoms passing thru periodic
|
|
boundaries.
|
|
</P>
|
|
<P>A vector of three quantites is calculated by this compute, which
|
|
are the x,y,z coordinates of the center of mass.
|
|
</P>
|
|
<P>IMPORTANT NOTE: The coordinates of an atom contribute to the
|
|
center-of-mass in "unwrapped" form, by using the image flags
|
|
associated with each atom. See the <A HREF = "dump.html">dump custom</A> command
|
|
for a discussion of "unwrapped" coordinates. See the Atoms section of
|
|
the <A HREF = "read_data.html">read_data</A> command for a discussion of image flags
|
|
and how they are set for each atom. You can reset the image flags
|
|
(e.g. to 0) before invoking this compute by using the <A HREF = "set.html">set
|
|
image</A> command.
|
|
</P>
|
|
<P><B>Output info:</B>
|
|
</P>
|
|
<P>This compute calculates a global vector of length 3, which can be
|
|
accessed by indices 1-3 by any command that uses global vector values
|
|
from a compute as input. See <A HREF = "Section_howto.html#howto_15">this
|
|
section</A> for an overview of LAMMPS output
|
|
options.
|
|
</P>
|
|
<P>The vector values are "intensive". The vector values will be in
|
|
distance <A HREF = "units.html">units</A>.
|
|
</P>
|
|
<P><B>Restrictions:</B> none
|
|
</P>
|
|
<P><B>Related commands:</B>
|
|
</P>
|
|
<P><A HREF = "compute_com_chunk.html">compute com/chunk</A>
|
|
</P>
|
|
<P><B>Default:</B> none
|
|
</P>
|
|
</HTML>
|