forked from lijiext/lammps
92 lines
3.3 KiB
HTML
92 lines
3.3 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 bond/local command
|
|
</H3>
|
|
<P><B>Syntax:</B>
|
|
</P>
|
|
<PRE>compute ID group-ID bond/local input1 input2 ...
|
|
</PRE>
|
|
<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
|
|
|
|
<LI>bond/local = style name of this compute command
|
|
|
|
<LI>zero or more keywords may be appended
|
|
|
|
<LI>keyword = <I>dist</I> or <I>eng</I>
|
|
|
|
<PRE> <I>dist</I> = tabulate bond distances
|
|
<I>eng</I> = tablutate bond energies
|
|
</PRE>
|
|
|
|
</UL>
|
|
<P><B>Examples:</B>
|
|
</P>
|
|
<PRE>compute 1 all bond/local eng
|
|
compute 1 all bond/local dist eng
|
|
</PRE>
|
|
<P><B>Description:</B>
|
|
</P>
|
|
<P>Define a computation that calculates properties of individual bond
|
|
interactions. The number of datums generated, aggregated across all
|
|
processors, equals the number of bonds in the system.
|
|
</P>
|
|
<P>The local data stored by this command is generated by looping over all
|
|
the atoms owned on a processor and their bonds. A bond will only be
|
|
included if both atoms in the bond are in the specified compute group.
|
|
Any bonds that have been broken (see the <A HREF = "bond_style.html">bond_style</A>
|
|
command) by setting their bond type to 0 are not included. Bonds that
|
|
have been turned off (see the <A HREF = "fix_shake.html">fix shake</A> or
|
|
<A HREF = "delete_bonds.html">delete_bonds</A> commands) by setting their bond type
|
|
negative are written into the file, but their energy will be 0.0.
|
|
</P>
|
|
<P>Note that as atoms migrate from processor to processor, there will be
|
|
no consistent ordering of the entries within the local vector or array
|
|
from one timestep to the next. The only consistency that is
|
|
guaranteed is that the ordering on a particular timestep will be the
|
|
same for local vectors or arrays generated by other compute commands.
|
|
For example, bond output from the <A HREF = "compute_property_local.html">compute
|
|
property/local</A> command can be combined
|
|
with data from this command and output by the <A HREF = "dump.html">dump local</A>
|
|
command in a consistent way.
|
|
</P>
|
|
<P>Here is an example of how to do this:
|
|
</P>
|
|
<PRE>compute 1 all property/local batom1 batom2 btype
|
|
compute 2 all bond/local dist eng
|
|
dump 1 all local 1000 tmp.dump index c_1[1] c_1[2] c_1[3] c_2[1] c_2[2]
|
|
</PRE>
|
|
<P><B>Output info:</B>
|
|
</P>
|
|
<P>This compute calculates a local vector or local array depending on the
|
|
number of keywords. The length of the vector or number of rows in the
|
|
array is the number of bonds. If a single keyword is specified, a
|
|
local vector is produced. If two or more keywords are specified, a
|
|
local array is produced where the number of columns = the number of
|
|
keywords. The vector or array can be accessed by any command that
|
|
uses local 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 output for <I>dist</I> will be in distance <A HREF = "units.html">units</A>. The
|
|
output for <I>eng</I> will be in energy <A HREF = "units.html">units</A>.
|
|
</P>
|
|
<P><B>Restrictions:</B> none
|
|
</P>
|
|
<P><B>Related commands:</B>
|
|
</P>
|
|
<P><A HREF = "dump.html">dump local</A>, <A HREF = "compute_property_local.html">compute
|
|
property/local</A>
|
|
</P>
|
|
<P><B>Default:</B> none
|
|
</P>
|
|
</HTML>
|