change convergence criteria in min_spin

src/SPIN/min_spin.cpp

@@ -167,7 +167,7 @@ int MinSpin::iterate(int maxiter)
     // sync across replicas if running multi-replica minimization
 
     if (update->ftol > 0.0) {
-      fmdotfm = fmnorm_sqr();
+      fmdotfm = max_torque();
       if (update->multireplica == 0) {
         if (fmdotfm < update->ftol*update->ftol) return FTOL;
       } else {
@@ -331,3 +331,43 @@ double MinSpin::fmnorm_sqr()
   return norm2_sqr;
 }
 
+/* ----------------------------------------------------------------------
+   compute and return  max_i||mag. torque_i||_2
+------------------------------------------------------------------------- */
+
+double MinSpin::max_torque()
+{
+  double fmsq,fmaxsqone,fmaxsqloc,fmaxsqall;
+  int nlocal = atom->nlocal;
+  double hbar = force->hplanck/MY_2PI;
+  double tx,ty,tz;
+  double **sp = atom->sp;
+  double **fm = atom->fm;
+
+  fmsq = fmaxsqone = fmaxsqloc = fmaxsqall = 0.0;
+  for (int i = 0; i < nlocal; i++) {
+    tx = fm[i][1] * sp[i][2] - fm[i][2] * sp[i][1];
+    ty = fm[i][2] * sp[i][0] - fm[i][0] * sp[i][2];
+    tz = fm[i][0] * sp[i][1] - fm[i][1] * sp[i][0];
+    fmsq = tx * tx + ty * ty + tz * tz;
+    fmaxsqone = MAX(fmaxsqone,fmsq);
+  }
+
+  // finding max fm on this replica
+
+  fmaxsqloc = fmaxsqone;
+  MPI_Allreduce(&fmaxsqone,&fmaxsqloc,1,MPI_DOUBLE,MPI_MAX,world);
+
+  // finding max fm over all replicas, if necessary
+  // this communicator would be invalid for multiprocess replicas
+
+  fmaxsqall = fmaxsqloc;
+  if (update->multireplica == 1) {
+    fmaxsqall = fmaxsqloc;
+    MPI_Allreduce(&fmaxsqloc,&fmaxsqall,1,MPI_DOUBLE,MPI_MAX,universe->uworld);
+  }
+
+  // multiply it by hbar so that units are in eV
+
+  return sqrt(fmaxsqall) * hbar;
+}

src/SPIN/min_spin.h

@@ -36,6 +36,7 @@ class MinSpin : public Min {
   double evaluate_dt();
   void advance_spins(double);
   double fmnorm_sqr();
+  double max_torque();
 
  private: