git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@26 f3b2605a-c512-4ea7-a41b-209d697bcdaa

src/fix_temp_rescale.cpp

@@ -0,0 +1,170 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   www.cs.sandia.gov/~sjplimp/lammps.html
+   Steve Plimpton, sjplimp@sandia.gov, Sandia National Laboratories
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under 
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#include "string.h"
+#include "stdlib.h"
+#include "math.h"
+#include "fix_temp_rescale.h"
+#include "atom.h"
+#include "force.h"
+#include "group.h"
+#include "update.h"
+#include "domain.h"
+#include "region.h"
+#include "comm.h"
+#include "temperature.h"
+#include "error.h"
+
+/* ---------------------------------------------------------------------- */
+
+FixTempRescale::FixTempRescale(int narg, char **arg) : Fix(narg, arg)
+{
+  if (narg < 8) error->all("Illegal fix temp/rescale command");
+  nevery = atoi(arg[3]);
+  if (nevery <= 0) error->all("Illegal fix temp/rescale command");
+
+  t_start = atof(arg[4]);
+  t_end = atof(arg[5]);
+  t_window = atof(arg[6]);
+  fraction = atof(arg[7]);
+
+  // optional args
+
+  iregion = -1;
+
+  int iarg = 8;
+  while (iarg < narg) {
+    if (strcmp(arg[iarg],"region") == 0) {
+      for (iregion = 0; iregion < domain->nregion; iregion++)
+	if (strcmp(arg[iarg+1],domain->regions[iregion]->id) == 0) break;
+      if (iregion == domain->nregion)
+	error->all("Fix temp/rescale region ID does not exist");
+      iarg += 2;
+    } else error->all("Illegal fix temp/rescale command");
+  }
+
+  // create a new temperature full or region style with fix ID and fix group
+
+  char **newarg = new char*[4];
+  newarg[0] = id;
+  newarg[1] = group->names[igroup];
+  if (iregion == -1) {
+    newarg[2] = "full";
+    force->add_temp(3,newarg,1);
+  } else {
+    newarg[2] = "region";
+    newarg[3] = domain->regions[iregion]->id;
+    force->add_temp(4,newarg,1);
+  }
+  delete [] newarg;
+
+  temperature = force->find_temp(id);
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixTempRescale::setmask()
+{
+  int mask = 0;
+  mask |= END_OF_STEP;
+  mask |= THERMO;
+  return mask;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixTempRescale::init()
+{
+  energy = 0.0;
+  efactor = (0.5 * force->boltz * temperature->dof);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixTempRescale::end_of_step()
+{
+  double t_current = temperature->compute();
+  double delta = update->ntimestep - update->beginstep;
+  delta /= update->endstep - update->beginstep;
+  double t_target = t_start + delta * (t_end-t_start);
+
+  if (fabs(t_current-t_target) > t_window) {
+    t_target = t_current - fraction*(t_current-t_target);
+    double factor = sqrt(t_target/t_current);
+
+    double **x = atom->x;
+    double **v = atom->v;
+    int *mask = atom->mask;
+    int nlocal = atom->nlocal;
+
+    if (iregion == -1) {
+      energy += (t_current-t_target) * efactor;
+      for (int i = 0; i < nlocal; i++) {
+	if (mask[i] & groupbit) {
+	  v[i][0] *= factor;
+	  v[i][1] *= factor;
+	  v[i][2] *= factor;
+	}
+      }
+
+    } else {
+      efactor = (0.5 * force->boltz * temperature->dof);
+      energy += (t_current-t_target) * efactor;
+      for (int i = 0; i < nlocal; i++) {
+	if (mask[i] & groupbit &&
+	    domain->regions[iregion]->match(x[i][0],x[i][1],x[i][2])) {
+	  v[i][0] *= factor;
+	  v[i][1] *= factor;
+	  v[i][2] *= factor;
+	}
+      }
+    }
+  } else energy = 0.0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixTempRescale::modify_param(int narg, char **arg)
+{
+  if (strcmp(arg[0],"temp") == 0) {
+    if (narg < 2) error->all("Illegal fix_modify command");
+    temperature = force->find_temp(arg[1]);
+    if (temperature == NULL)
+      error->all("Could not find fix_modify temperature ID");
+    if (temperature->igroup != igroup && comm->me == 0)
+      error->warning("Group for fix_modify temp != fix group");
+    if (strcmp(temperature->style,"region") == 0 && iregion == -1 && 
+	comm->me == 0)
+      error->warning("Temperature for temp/rescale is style region");
+    return 2;
+  }
+  return 0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixTempRescale::thermo_fields(int n, int *flags, char **keywords)
+{
+  if (n == 0) return 1;
+  flags[0] = 3;
+  strcpy(keywords[0],"EngTRscl");
+  return 1;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixTempRescale::thermo_compute(double *values)
+{
+  values[0] = energy;
+  return 1;
+}