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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@13619 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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sjplimp 2015-07-16 22:35:06 +00:00
parent a2c475b1a2
commit 2e4b4ba786
2 changed files with 13 additions and 2 deletions
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8
doc/fix_momentum.html
View File

@ -22,17 +22,20 @@
<LI>N = adjust the momentum every this many timesteps
one or more keyword/value pairs may be appended
<LI>keyword = <I>linear</I> or <I>angular</I>
<LI>keyword = <I>linear</I> or <I>angular</I> or <I>rescale</I>
<PRE> <I>linear</I> values = xflag yflag zflag
xflag,yflag,zflag = 0/1 to exclude/include each dimension
<I>angular</I> values = none
</PRE>
<PRE> <I>rescale</I> values = none
</PRE>
</UL>
<P><B>Examples:</B>
</P>
<PRE>fix 1 all momentum 1 linear 1 1 0
fix 1 all momentum 1 linear 1 1 1 rescale
fix 1 all momentum 100 linear 1 1 1 angular
</PRE>
<P><B>Description:</B>
@ -55,6 +58,9 @@ a subset of them) does not drift or rotate during the simulation due
to random perturbations (e.g. <A HREF = "fix_langevin.html">fix langevin</A>
thermostatting).
</P>
<P>The <I>rescale</I> keyword enables conserving the kinetic energy of the group
of atoms by rescaling the velocities after the momentum was removed.
</P>
<P>Note that the <A HREF = "velocity.html">velocity</A> command can be used to create
initial velocities with zero aggregate linear and/or angular momentum.
</P>

7
doc/fix_momentum.txt
View File

@ -16,15 +16,17 @@ ID, group-ID are documented in "fix"_fix.html command :ulb,l
momentum = style name of this fix command :l
N = adjust the momentum every this many timesteps
one or more keyword/value pairs may be appended :l
keyword = {linear} or {angular} :l
keyword = {linear} or {angular} or {rescale} :l
{linear} values = xflag yflag zflag
xflag,yflag,zflag = 0/1 to exclude/include each dimension
{angular} values = none :pre
{rescale} values = none :pre
:ule
[Examples:]
fix 1 all momentum 1 linear 1 1 0
fix 1 all momentum 1 linear 1 1 1 rescale
fix 1 all momentum 100 linear 1 1 1 angular :pre
[Description:]
@ -47,6 +49,9 @@ a subset of them) does not drift or rotate during the simulation due
to random perturbations (e.g. "fix langevin"_fix_langevin.html
thermostatting).
The {rescale} keyword enables conserving the kinetic energy of the group
of atoms by rescaling the velocities after the momentum was removed.
Note that the "velocity"_velocity.html command can be used to create
initial velocities with zero aggregate linear and/or angular momentum.