bug fix for fix GCMC w/ fix shake, enhance of fix wall/gran/region with restarting

doc/README

@@ -91,6 +91,3 @@ This will install virtualenv from the Python Package Index.
 ----------------
 
 Installing prerequisites for PDF build
-
-
-

doc/src/compute_pe_atom.txt

@@ -72,9 +72,10 @@ compute        peratom all pe/atom
 compute        pe all reduce sum c_peratom
 thermo_style   custom step temp etotal press pe c_pe :pre
 
-NOTE: The per-atom energy does not any Lennard-Jones tail corrections
+NOTE: The per-atom energy does not include any Lennard-Jones tail
-invoked by the "pair_modify tail yes"_pair_modify.html command, since
+corrections to the energy added by the "pair_modify tail
-those are global contributions to the system energy.
+yes"_pair_modify.html command, since those are contributions to the
+global system energy.
 
 [Output info:]
 

doc/src/compute_stress_atom.txt

@@ -133,6 +133,11 @@ compute        p all reduce sum c_peratom\[1\] c_peratom\[2\] c_peratom\[3\]
 variable       press equal -(c_p\[1\]+c_p\[2\]+c_p\[3\])/(3*vol)
 thermo_style   custom step temp etotal press v_press :pre
 
+NOTE: The per-atom stress does not include any Lennard-Jones tail
+corrections to the pressure added by the "pair_modify tail
+yes"_pair_modify.html command, since those are contributions to the
+global system pressure.
+
 [Output info:]
 
 This compute calculates a per-atom array with 6 columns, which can be

doc/src/fix_wall_gran_region.txt

@@ -163,16 +163,20 @@ info on how to re-specify a fix in an input script that reads a
 restart file, so that the operation of the fix continues in an
 uninterrupted fashion.
 
-Note that info about region definitions is NOT included in restart
+NOTE: Information about region definitions is NOT included in restart
-files.  So you must re-define your region and if it is a moving
+files, as discussed on the "read_restart"_read_restart.html doc page.
-region, define its motion attributes in a way that is consistent with
+So you must re-define your region and if it is a moving region, define
-the simulation that wrote the restart file.  In particular, if you
+its motion attributes in a way that is consistent with the simulation
-want to change its motion attributes (e.g. its velocity), then you
+that wrote the restart file.  In particular, if you want to change the
-should insure the postition/orientation of the region at the initial
+region motion attributes (e.g. its velocity), then you should ensure
-restart timestep is the same as it was on the timestep the restart
+the postition/orientation of the region at the initial restart
-file was written.  If this is not possible, then you may need to
+timestep is the same as it was on the timestep the restart file was
-ignore info in the restart file by defining a new fix wall/gran/region
+written.  If this is not possible, you may need to ignore info in the
-command in your restart script (e.g. with a different fix ID).
+restart file by defining a new fix wall/gran/region command in your
+restart script, e.g. with a different fix ID.  Or if you want to keep
+the shear history info but discard the region motion information, you
+can use the same fix ID for fix wall/gran/region, but assign it a
+region with a different region ID.
 
 None of the "fix_modify"_fix_modify.html options are relevant to this
 fix.  No global or per-atom quantities are stored by this fix for

doc/src/read_restart.txt

@@ -197,12 +197,13 @@ was used in the input script that wrote the restart file.
 If a match is found, LAMMPS prints a message indicating that the fix
 is being re-enabled.  If no match is found before the first run or
 minimization is performed by the new script, the "state" information
-for the saved fix is discarded.  LAMMPS will also print a list of
+for the saved fix is discarded.  At the time the discard occurs,
-fixes for which the information is being discarded.  See the doc pages
+LAMMPS will also print a list of fixes for which the information is
-for individual fixes for info on which ones can be restarted in this
+being discarded.  See the doc pages for individual fixes for info on
-manner.  Note that fixes which are created internally by other LAMMPS
+which ones can be restarted in this manner.  Note that fixes which are
-commands (computes, fixes, etc) will have style names which are
+created internally by other LAMMPS commands (computes, fixes, etc)
-all-capitalized, and IDs which are generated internally.
+will have style names which are all-capitalized, and IDs which are
+generated internally.
 
 Likewise, the "computes"_fix.html used for a simulation are not stored
 in the restart file.  This means the new input script should specify
@@ -219,12 +220,16 @@ described in the previous paragraph, so that the compute can continue
 its calculations in a consistent manner.
 
 NOTE: There are a handful of commands which can be used before or
-between runs which require a system initialization.  Examples include
+between runs which may require a system initialization.  Examples
-the "balance", "displace_atoms", and "delete_atoms" commands.  This is
+include the "balance", "displace_atoms", "delete_atoms", "set" (some
-because they may migrate atoms to new processors.  Thus they will also
+options), and "velocity" (some options) commands.  This is because
-discard unused "state" information from fixes.  This means that, if
+they can migrate atoms to new processors.  Thus they will also discard
-desired, you must re-specify the relevant fixes and computes (which
+unused "state" information from fixes.  You will know the discard has
-create fixes) before those commands are used.
+occurred because a list of discarded fixes will be printed to the
+screen and log file, as explained above.  This means that if you wish
+to retain that info in a restarted run, you must re-specify the
+relevant fixes and computes (which create fixes) before those commands
+are used.
 
 Some pair styles, like the "granular pair styles"_pair_gran.html, also
 use a fix to store "state" information that persists from timestep to

src/GRANULAR/fix_wall_gran.cpp

@@ -53,7 +53,6 @@ FixWallGran::FixWallGran(LAMMPS *lmp, int narg, char **arg) :
   if (!atom->sphere_flag)
     error->all(FLERR,"Fix wall/gran requires atom style sphere");
 
-  restart_peratom = 1;
   create_attribute = 1;
 
   // set interaction style
@@ -65,8 +64,8 @@ FixWallGran::FixWallGran(LAMMPS *lmp, int narg, char **arg) :
   //else if (strcmp(arg[3],"bonded/history") == 0) pairstyle = BONDED_HISTORY;
   else error->all(FLERR,"Invalid fix wall/gran interaction style");
 
-  history = 1;
+  history = restart_peratom = 1;
-  if (pairstyle == HOOKE) history = 0;
+  if (pairstyle == HOOKE) history = restart_peratom = 0;
 
   // wall/particle coefficients
 

src/GRANULAR/fix_wall_gran_region.cpp

@@ -101,20 +101,27 @@ void FixWallGranRegion::init()
     error->all(FLERR,"Region ID for fix wall/gran/region does not exist");
   region = domain->regions[iregion];
 
-  // region displacement and orientation theta at previous step
   // check if region properties changed between runs
+  // reset if restart info was inconsistent
 
-  if (motion_resetflag) {
+  if (strcmp(idregion,region->id) != 0 ||
-    if (comm->me == 0) {
+      strcmp(region_style,region->style) != 0 ||
-      char str[128];
+      nregion != region->nregion) {
-      sprintf(str,"Properties for region %s do not match restart file, "
+    char str[256];
-              "resetting its motion",idregion);
+    sprintf(str,"Region properties for region %s changed between runs, "
-      error->warning(FLERR,str);
+            "resetting its motion",idregion);
-    }
+    error->warning(FLERR,str);
     region->reset_vel();
-  }  
+  }
-}
 
+  if (motion_resetflag){    
+    char str[256];
+    sprintf(str,"Region properties for region %s are inconsistent "
+            "with restart file, resetting its motion",idregion);
+    error->warning(FLERR,str);
+    region->reset_vel();
+  }
+}
 
 /* ---------------------------------------------------------------------- */
 
@@ -483,19 +490,9 @@ int FixWallGranRegion::size_restart(int nlocal)
 void FixWallGranRegion::write_restart(FILE *fp)
 {
   if (comm->me) return;
-  int size_id_str = (strlen(region->id) + 1) * sizeof(char);
+  int len = 0;
-  int size_style_str = (strlen(region->style) + 1) * sizeof(char);
+  region->length_restart_string(len);
-  int size_tot = sizeof(int) + size_id_str + 
+  fwrite(&len, sizeof(int),1,fp);
-    sizeof(int) + size_style_str + sizeof(int) + 
-    region->size_restart*sizeof(double);
-
-  fwrite(&size_tot,sizeof(int),1,fp);
-  fwrite(&size_id_str,sizeof(int),1,fp);
-  fwrite(region->id,sizeof(char),size_id_str,fp);
-  fwrite(&size_style_str,sizeof(int),1,fp);
-  fwrite(region->style,sizeof(char),size_style_str,fp);  
-  fwrite(&region->nregion,sizeof(int),1,fp);
-
   region->write_restart(fp);
 }
 
@@ -505,44 +502,6 @@ void FixWallGranRegion::write_restart(FILE *fp)
 
 void FixWallGranRegion::restart(char *buf)
 {
-  int n = 0;  
+  int n = 0;
-  int size_id_str = buf[n];
+  if (!region->restart(buf,n)) motion_resetflag = 1;  
-  n += sizeof(int);
-  char *region_id_restart = new char[size_id_str];
-  for (int i = 0; i < size_id_str; i++){
-    region_id_restart[i] = buf[n++];  
-  }
-  
-  int size_style_str = buf[n];
-  n += sizeof(int);
-  char *region_style_restart = new char[size_style_str];
-  for (int i = 0; i < size_style_str; i++)
-    region_style_restart[i] = buf[n++];  
-  
-  int nregion_restart = buf[n];
-  n += sizeof(int);
-
-  if (check_consistent_region(region,region_id_restart,
-                              region_style_restart,nregion_restart))
-    region->restart(buf,n);
-  else motion_resetflag = 1;
-
-  delete [] region_id_restart;
-  delete [] region_style_restart;
-}
-
-
-/* ----------------------------------------------------------------------
-   check that region id/style/number of sub-regions are consistent
-------------------------------------------------------------------------- */
-
-int FixWallGranRegion::check_consistent_region(Region *region, 
-                                               char* region_id, 
-                                               char* region_style, int nregion)
-{
-  if (strcmp(region_id, region->id) != 0 ||
-      strcmp(region_style, region->style) != 0 ||
-      nregion != region->nregion)
-    return 0;       
-  return 1;
 }

src/GRANULAR/fix_wall_gran_region.h

@@ -62,7 +62,6 @@ class FixWallGranRegion : public FixWallGran {
                          //    vel info is to be reset
 
   void update_contacts(int, int);
-  int check_consistent_region(Region *, char*, char*, int);
 };
 
 }

src/MC/fix_bond_create.cpp

@@ -40,7 +40,8 @@ using namespace FixConst;
 
 FixBondCreate::FixBondCreate(LAMMPS *lmp, int narg, char **arg) :
   Fix(lmp, narg, arg),
-  bondcount(NULL), partner(NULL), finalpartner(NULL), distsq(NULL), created(NULL), copy(NULL), random(NULL)
+  bondcount(NULL), partner(NULL), finalpartner(NULL), distsq(NULL), 
+  created(NULL), copy(NULL), random(NULL)
 {
   if (narg < 8) error->all(FLERR,"Illegal fix bond/create command");
 

src/MC/fix_gcmc.cpp

@@ -2108,6 +2108,12 @@ double FixGCMC::energy_full()
   int eflag = 1;
   int vflag = 0;
 
+  // clear forces so they don't accumulate over multiple
+  // calls within fix gcmc timestep, e.g. for fix shake
+  
+  size_t nbytes = sizeof(double) * (atom->nlocal + atom->nghost);
+  if (nbytes) memset(&atom->f[0][0],0,3*nbytes);
+
   if (modify->n_pre_force) modify->pre_force(vflag);
 
   if (force->pair) force->pair->compute(eflag,vflag);
@@ -2121,9 +2127,18 @@ double FixGCMC::energy_full()
 
   if (force->kspace) force->kspace->compute(eflag,vflag);
 
+  // unlike Verlet, not performing a reverse_comm() or forces here
+  // b/c GCMC does not care about forces
+  // don't think it will mess up energy due to any post_force() fixes
+
   if (modify->n_post_force) modify->post_force(vflag);
   if (modify->n_end_of_step) modify->end_of_step();
 
+  // NOTE: all fixes with THERMO_ENERGY mask set and which
+  //   operate at pre_force() or post_force() or end_of_step()
+  //   and which user has enable via fix_modify thermo yes,
+  //   will contribute to total MC energy via pe->compute_scalar()
+
   update->eflag_global = update->ntimestep;
   double total_energy = c_pe->compute_scalar();
 

src/fix_recenter.cpp

@@ -54,8 +54,6 @@ FixRecenter::FixRecenter(LAMMPS *lmp, int narg, char **arg) :
   global_freq = 1;
   dynamic_group_allow = 1;
 
-/* ---------------------------------------------------------------------- */
-
   if (strcmp(arg[3],"NULL") == 0) xflag = 0;
   else if (strcmp(arg[3],"INIT") == 0) xinitflag = 1;
   else xcom = force->numeric(FLERR,arg[3]);

src/lammps.cpp

@@ -707,7 +707,7 @@ void LAMMPS::init()
   atom->init();          // atom must come after force and domain
                          //   atom deletes extra array
                          //   used by fix shear_history::unpack_restart()
-                         //   when force->pair->gran_history creates fix ??
+                         //     when force->pair->gran_history creates fix
                          //   atom_vec init uses deform_vremap
   modify->init();        // modify must come after update, force, atom, domain
   neighbor->init();      // neighbor must come after force, modify

src/region.cpp

@@ -42,10 +42,6 @@ Region::Region(LAMMPS *lmp, int narg, char **arg) : Pointers(lmp)
   xstr = ystr = zstr = tstr = NULL;
   dx = dy = dz = 0.0;
 
-  // used by set_velocity() even if no rotation specified
-
-  point[0] = point[1] = point[2] = 0.0;
-
   size_restart = 5;
   reset_vel();
   copymode = 0;
@@ -398,7 +394,6 @@ void Region::options(int narg, char **arg)
     else error->all(FLERR,"Illegal region command");
   }
 
-
   // error check
 
   if ((moveflag || rotateflag) &&
@@ -524,42 +519,95 @@ void Region::velocity_contact(double *vwall, double *x, int ic)
 {
   Contact c = contact[ic];
   double xc[3];
-  xc[0] = x[0] - contact[ic].delx;
-  xc[1] = x[1] - contact[ic].dely;
-  xc[2] = x[2] - contact[ic].delz;
-  
-  vwall[0] = v[0] + omega[1]*(xc[2] - rpoint[2]) - omega[2]*(xc[1] - rpoint[1]);
-  vwall[1] = v[1] + omega[2]*(xc[0] - rpoint[0]) - omega[0]*(xc[2] - rpoint[2]);
-  vwall[2] = v[2] + omega[0]*(xc[1] - rpoint[1]) - omega[1]*(xc[0] - rpoint[0]);
 
-  if (varshape && contact[ic].varflag) velocity_contact_shape(vwall,xc);
+  vwall[0] = vwall[1] = vwall[2] = 0.0;
+
+  if (moveflag){
+    vwall[0] = v[0];
+    vwall[1] = v[1];
+    vwall[2] = v[2];
+  }
+  if (rotateflag){
+    xc[0] = x[0] - contact[ic].delx;
+    xc[1] = x[1] - contact[ic].dely;
+    xc[2] = x[2] - contact[ic].delz;
+    vwall[0] += omega[1]*(xc[2] - rpoint[2]) - omega[2]*(xc[1] - rpoint[1]);
+    vwall[1] += omega[2]*(xc[0] - rpoint[0]) - omega[0]*(xc[2] - rpoint[2]);
+    vwall[2] += omega[0]*(xc[1] - rpoint[1]) - omega[1]*(xc[0] - rpoint[0]);
+  }
+
+  if (varshape && contact[ic].varflag) velocity_contact_shape(vwall, xc);
+}
+
+
+/* ----------------------------------------------------------------------
+   increment length of restart buffer based on region info
+   used by restart of fix/wall/gran/region
+------------------------------------------------------------------------- */
+
+void Region::length_restart_string(int &n)
+{
+  n += sizeof(int) + strlen(id)+1 + 
+    sizeof(int) + strlen(style)+1 + sizeof(int) +
+    size_restart*sizeof(double);
 }
 
 /* ----------------------------------------------------------------------
-   region writes its current position/angle
+   region writes its current style, id, number of sub-regions 
+     and position/angle
    needed by fix/wall/gran/region to compute velocity by differencing scheme
 ------------------------------------------------------------------------- */
 
 void Region::write_restart(FILE *fp)
 {
+  int sizeid = (strlen(id)+1);
+  int sizestyle = (strlen(style)+1);
+  fwrite(&sizeid, sizeof(int), 1, fp);
+  fwrite(id, 1, sizeid, fp);
+  fwrite(&sizestyle, sizeof(int), 1, fp);
+  fwrite(style, 1, sizestyle, fp);  
+  fwrite(&nregion,sizeof(int),1,fp);
+
   fwrite(prev, sizeof(double), size_restart, fp);  
 }
 
 /* ----------------------------------------------------------------------
-   region reads its previous position/angle
+   region reads style, id, number of sub-regions from restart file
+     if they match current region, also read previous position/angle
    needed by fix/wall/gran/region to compute velocity by differencing scheme
 ------------------------------------------------------------------------- */
 
-int Region::restart(char *buf, int n)
+int Region::restart(char *buf, int &n)
 {
+  int sizeid = buf[n];
+  n += sizeof(int);
+  char *restart_id = new char[sizeid];
+  for (int i = 0; i < sizeid; i++)
+    restart_id[i] = buf[n++];    
+  if (strcmp(restart_id,id) != 0) return 0;
+
+  int sizestyle = buf[n];
+  n += sizeof(int);
+  char *restart_style = new char[sizestyle];
+  for (int i = 0; i < sizestyle; i++)
+    restart_style[i] = buf[n++];  
+  if (strcmp(restart_style,style) != 0) return 0;    
+
+  int restart_nreg = buf[n];
+  n += sizeof(int);
+  if (restart_nreg != nregion) return 0;
+
   char *rlist = new char[size_restart*sizeof(double)];  
   for (int i = 0; i < size_restart*sizeof(double); i++)
     rlist[i] = buf[n++]; 
-  for (int i = 0; i < size_restart; i++) {
+  for (int i = 0; i < size_restart; i++){
     prev[i] = ((double *)rlist)[i];
   }
+  
   delete [] rlist;
-  return n;
+  delete [] restart_id;
+  delete [] restart_style;
+  return 1;
 }
 
 /* ----------------------------------------------------------------------
@@ -568,6 +616,5 @@ int Region::restart(char *buf, int n)
 
 void Region::reset_vel()
 {
-  for (int i = 0; i < size_restart; i++)
+  for (int i = 0; i < size_restart; i++) prev[i] = 0;
-    prev[i] = 0;
 }

src/region.h

@@ -59,8 +59,7 @@ class Region : protected Pointers {
   double rpoint[3];	      // current origin of rotation axis
   double omega[3];	      // angular velocity
   double rprev;               // speed of time-dependent radius, if applicable
-  double xcenter[3];          // translated/rotated center of cylinder/sphere
+  double xcenter[3];          // translated/rotated center of cylinder/sphere (only used if varshape)
-                              //   only used with varshape
   double prev[5];             // stores displacement (X3), angle and if 
                               //  necessary, region variable size (e.g. radius)
                               //  at previous time step
@@ -84,7 +83,8 @@ class Region : protected Pointers {
   virtual void set_velocity();
   void velocity_contact(double *, double *, int);
   virtual void write_restart(FILE *);
-  virtual int restart(char *, int);
+  virtual int restart(char *, int&);
+  virtual void length_restart_string(int&);
   virtual void reset_vel();
 
   // implemented by each region, not called by other classes
@@ -106,12 +106,11 @@ class Region : protected Pointers {
   void options(int, char **);
   void point_on_line_segment(double *, double *, double *, double *);
   void forward_transform(double &, double &, double &);
-  double point[3],runit[3];
 
  private:
   char *xstr,*ystr,*zstr,*tstr;
   int xvar,yvar,zvar,tvar;
-  double axis[3];
+  double axis[3],point[3],runit[3];
 
   void inverse_transform(double &, double &, double &);
   void rotate(double &, double &, double &, double);

src/region_intersect.cpp

@@ -91,11 +91,8 @@ RegIntersect::RegIntersect(LAMMPS *lmp, int narg, char **arg) :
   // for near contacts and touching contacts
 
   cmax = 0;
-  size_restart = 0;
+  for (int ilist = 0; ilist < nregion; ilist++)
-  for (int ilist = 0; ilist < nregion; ilist++){
     cmax += regions[list[ilist]]->cmax;
-    size_restart += regions[list[ilist]]->size_restart;
-  }
   contact = new Contact[cmax];
 
   tmax = 0;
@@ -274,6 +271,7 @@ void RegIntersect::pretransform()
     regions[list[ilist]]->pretransform();
 }
 
+
 /* ----------------------------------------------------------------------
    get translational/angular velocities of all subregions
 ------------------------------------------------------------------------- */
@@ -285,6 +283,19 @@ void RegIntersect::set_velocity()
     regions[list[ilist]]->set_velocity();
 }
 
+/* ----------------------------------------------------------------------
+   increment length of restart buffer based on region info
+   used by restart of fix/wall/gran/region
+------------------------------------------------------------------------- */
+
+void RegIntersect::length_restart_string(int& n)
+{
+  n += sizeof(int) + strlen(id)+1 + 
+    sizeof(int) + strlen(style)+1 + sizeof(int);
+  for (int ilist = 0; ilist < nregion; ilist++)
+    domain->regions[list[ilist]]->length_restart_string(n);
+
+}
 /* ----------------------------------------------------------------------
    region writes its current position/angle
    needed by fix/wall/gran/region to compute velocity by differencing scheme
@@ -292,8 +303,17 @@ void RegIntersect::set_velocity()
 
 void RegIntersect::write_restart(FILE *fp)
 {
-  for (int ilist = 0; ilist < nregion; ilist++)
+  int sizeid = (strlen(id)+1);
+  int sizestyle = (strlen(style)+1);
+  fwrite(&sizeid, sizeof(int), 1, fp);
+  fwrite(id, 1, sizeid, fp);
+  fwrite(&sizestyle, sizeof(int), 1, fp);
+  fwrite(style, 1, sizestyle, fp);  
+  fwrite(&nregion,sizeof(int),1,fp);
+
+  for (int ilist = 0; ilist < nregion; ilist++){
     domain->regions[list[ilist]]->write_restart(fp);
+  }
 }
 
 /* ----------------------------------------------------------------------
@@ -301,11 +321,33 @@ void RegIntersect::write_restart(FILE *fp)
    needed by fix/wall/gran/region to compute velocity by differencing scheme
 ------------------------------------------------------------------------- */
 
-int RegIntersect::restart(char *buf, int n)
+int RegIntersect::restart(char *buf, int& n)
 {
-  for (int ilist = 0; ilist < nregion; ilist++)
+  int sizeid = buf[n];
-    n = domain->regions[list[ilist]]->restart(buf, n);
+  n += sizeof(int);
-  return n;
+  char *restart_id = new char[sizeid];
+  for (int i = 0; i < sizeid; i++)
+    restart_id[i] = buf[n++];    
+  if (strcmp(restart_id,id) != 0) return 0;
+
+  int sizestyle = buf[n];
+  n += sizeof(int);
+
+  char *restart_style = new char[sizestyle];
+  for (int i = 0; i < sizestyle; i++)
+    restart_style[i] = buf[n++];  
+  if (strcmp(restart_style,style) != 0) return 0;    
+
+  int restart_nreg = buf[n];
+  n += sizeof(int);
+  if (restart_nreg != nregion) return 0;
+
+  for (int ilist = 0; ilist < nregion; ilist++){
+    if (!domain->regions[list[ilist]]->restart(buf, n)){
+      return 0;
+    }
+  }
+  return 1; 
 }
 
 /* ----------------------------------------------------------------------

src/region_intersect.h

@@ -35,8 +35,9 @@ class RegIntersect : public Region {
   void shape_update();
   void pretransform();
   void set_velocity();
+  void length_restart_string(int&);
   void write_restart(FILE *);
-  int restart(char *, int);
+  int restart(char *, int&);
   void reset_vel();
 
  private:

src/region_union.cpp

@@ -85,11 +85,8 @@ RegUnion::RegUnion(LAMMPS *lmp, int narg, char **arg) : Region(lmp, narg, arg)
   // for near contacts and touching contacts
 
   cmax = 0;
-  size_restart = 0;
+  for (int ilist = 0; ilist < nregion; ilist++)
-  for (int ilist = 0; ilist < nregion; ilist++){
     cmax += regions[list[ilist]]->cmax;
-    size_restart += regions[list[ilist]]->size_restart;
-  }
   contact = new Contact[cmax];
 
   tmax = 0;
@@ -279,6 +276,20 @@ void RegUnion::set_velocity()
   for (int ilist = 0; ilist < nregion; ilist++)
     regions[list[ilist]]->set_velocity();
 }
+
+/* ----------------------------------------------------------------------
+   increment length of restart buffer based on region info
+   used by restart of fix/wall/gran/region
+------------------------------------------------------------------------- */
+
+void RegUnion::length_restart_string(int& n)
+{
+  n += sizeof(int) + strlen(id)+1 + 
+    sizeof(int) + strlen(style)+1 + sizeof(int);
+  for (int ilist = 0; ilist < nregion; ilist++)
+    domain->regions[list[ilist]]->length_restart_string(n);
+
+}
 /* ----------------------------------------------------------------------
    region writes its current position/angle
    needed by fix/wall/gran/region to compute velocity by differencing scheme
@@ -286,8 +297,15 @@ void RegUnion::set_velocity()
 
 void RegUnion::write_restart(FILE *fp)
 {
+  int sizeid = (strlen(id)+1);
+  int sizestyle = (strlen(style)+1);
+  fwrite(&sizeid, sizeof(int), 1, fp);
+  fwrite(id, 1, sizeid, fp);
+  fwrite(&sizestyle, sizeof(int), 1, fp);
+  fwrite(style, 1, sizestyle, fp);  
+  fwrite(&nregion,sizeof(int),1,fp);
   for (int ilist = 0; ilist < nregion; ilist++)
-    domain->regions[list[ilist]]->write_restart(fp);
+    domain->regions[list[ilist]]->write_restart(fp);  
 }
 
 /* ----------------------------------------------------------------------
@@ -295,11 +313,30 @@ void RegUnion::write_restart(FILE *fp)
    needed by fix/wall/gran/region to compute velocity by differencing scheme
 ------------------------------------------------------------------------- */
 
-int RegUnion::restart(char *buf, int n)
+int RegUnion::restart(char *buf, int &n)
 {
-  for (int ilist = 0; ilist < nregion; ilist++)
+  int sizeid = buf[n];
-    n = domain->regions[list[ilist]]->restart(buf, n);
+  n += sizeof(int);
-  return n;
+  char *restart_id = new char[sizeid];
+  for (int i = 0; i < sizeid; i++)
+    restart_id[i] = buf[n++];    
+  if (strcmp(restart_id,id) != 0) return 0;
+
+  int sizestyle = buf[n];
+  n += sizeof(int);
+  char *restart_style = new char[sizestyle];
+  for (int i = 0; i < sizestyle; i++)
+    restart_style[i] = buf[n++];  
+  if (strcmp(restart_style,style) != 0) return 0;    
+
+  int restart_nreg = buf[n];
+  n += sizeof(int);
+  if (restart_nreg != nregion) return 0;
+
+  for (int ilist = 0; ilist < nregion; ilist++){
+    if (!domain->regions[list[ilist]]->restart(buf, n)) return 0;
+  }
+  return 1;
 }
 
 /* ----------------------------------------------------------------------

src/region_union.h

@@ -35,10 +35,10 @@ class RegUnion : public Region {
   void shape_update();
   void pretransform();
   void set_velocity();
+  void length_restart_string(int&);
   void write_restart(FILE *);
-  int restart(char *, int);
+  int restart(char *, int&);
   void reset_vel();
-
  private:
   char **idsub;
 };