git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@55 f3b2605a-c512-4ea7-a41b-209d697bcdaa

doc/fix_momentum.html

@@ -19,7 +19,8 @@
 
 <LI>momentum = style name of this fix command 
 
-<LI>one or more keyword/value pairs may be appended to the args 
+<LI>N = adjust the momentum every this many timesteps
+one or more keyword/value pairs may be appended to the args 
 
 <LI>keyword = <I>linear</I> or <I>angular</I> 
 
@@ -31,12 +32,14 @@
 </UL>
 <P><B>Examples:</B>
 </P>
-<PRE>fix 1 all momentum 1 linear 1 1 0 angular 
+<PRE>fix 1 all momentum 1 linear 1 1 0
+fix 1 all momentum 100 linear 1 1 1 angular 
 </PRE>
 <P><B>Description:</B>
 </P>
 <P>Zero the linear and/or angular momentum of the group of atoms every N
-timesteps by adjusting the velocities of the atoms.
+timesteps by adjusting the velocities of the atoms.  One (or both) of
+the <I>linear</I> or <I>angular</I> keywords must be specified.
 </P>
 <P>If the <I>linear</I> keyword is used, the linear momentum is zeroed by
 subtracting the center-of-mass velocity of the group from each atom.
@@ -53,7 +56,7 @@ to random perturbations (e.g. <A HREF = "fix_langevin.html">fix langevin</A>
 thermostatting).
 </P>
 <P>Note that the <A HREF = "velocity.html">velocity</A> command can be used to create
-velocities with zero aggregate linear and/or angular momentum.
+initial velocities with zero aggregate linear and/or angular momentum.
 </P>
 <P><B>Restrictions:</B> none
 </P>

doc/fix_momentum.txt

@@ -14,7 +14,7 @@ fix ID group-ID momentum N keyword values ... :pre
 
 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 to the args :l
 keyword = {linear} or {angular} :l
   {linear} values = xflag yflag zflag
@@ -24,12 +24,14 @@ keyword = {linear} or {angular} :l
 
 [Examples:]
 
-fix 1 all momentum 1 linear 1 1 0 angular :pre
+fix 1 all momentum 1 linear 1 1 0
+fix 1 all momentum 100 linear 1 1 1 angular :pre
 
 [Description:]
 
 Zero the linear and/or angular momentum of the group of atoms every N
-timesteps by adjusting the velocities of the atoms.
+timesteps by adjusting the velocities of the atoms.  One (or both) of
+the {linear} or {angular} keywords must be specified.
 
 If the {linear} keyword is used, the linear momentum is zeroed by
 subtracting the center-of-mass velocity of the group from each atom.
@@ -46,7 +48,7 @@ to random perturbations (e.g. "fix langevin"_fix_langevin.html
 thermostatting).
 
 Note that the "velocity"_velocity.html command can be used to create
-velocities with zero aggregate linear and/or angular momentum.
+initial velocities with zero aggregate linear and/or angular momentum.
 
 [Restrictions:] none
 

doc/fix_recenter.html

@@ -33,7 +33,10 @@
 </UL>
 <P><B>Examples:</B>
 </P>
-<PRE>fix 1 all recenter 1 1 1 0 
+<PRE>fix 1 all recenter 0.0 0.5 0.0 
+</PRE>
+<PRE>fix 1 all recenter INIT INIT NULL
+fix 1 all recenter INIT 0.0 0.0 units box 
 </PRE>
 <P><B>Description:</B>
 </P>

doc/fix_recenter.txt

@@ -25,7 +25,9 @@ keyword = {shift} or {units} :l
 
 [Examples:]
 
-fix 1 all recenter 1 1 1 0 :pre
+fix 1 all recenter 0.0 0.5 0.0 :pre
+fix 1 all recenter INIT INIT NULL
+fix 1 all recenter INIT 0.0 0.0 units box :pre
 
 [Description:]
 

src/fix_momentum.cpp

@@ -27,7 +27,7 @@
 
 FixMomentum::FixMomentum(int narg, char **arg) : Fix(narg, arg)
 {
-  if (narg != 7) error->all("Illegal fix momentum command");
+  if (narg < 4) error->all("Illegal fix momentum command");
   nevery = atoi(arg[3]);
   if (nevery <= 0) error->all("Illegal fix momentum command");
 

src/group.cpp

@@ -699,7 +699,7 @@ void Group::angmom(int igroup, double *cm, double *lmom)
       dy = (x[i][1] + ybox*yprd) - cm[1];
       dz = (x[i][2] + zbox*zprd) - cm[2];
       if (mass_require) massone = mass[type[i]];
-      massone = rmass[i];
+      else massone = rmass[i];
       p[0] += massone * (dy*v[i][2] - dz*v[i][1]);
       p[1] += massone * (dz*v[i][0] - dx*v[i][2]);
       p[2] += massone * (dx*v[i][1] - dy*v[i][0]);

src/pppm.cpp

@@ -18,6 +18,7 @@
 #include "mpi.h"
 #include "string.h"
 #include "stdio.h"
+#include "stdlib.h"
 #include "math.h"
 #include "pppm.h"
 #include "atom.h"