add support for loading plugins for fixes

examples/plugins/fix_nve2.cpp

@@ -0,0 +1,171 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   https://lammps.sandia.gov/, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   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 "fix_nve2.h"
+#include <cstring>
+#include "atom.h"
+#include "force.h"
+#include "update.h"
+#include "respa.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+using namespace FixConst;
+
+/* ---------------------------------------------------------------------- */
+
+FixNVE2::FixNVE2(LAMMPS *lmp, int narg, char **arg) :
+  Fix(lmp, narg, arg)
+{
+  if (strcmp(style,"nve/sphere") != 0 && narg < 3)
+    error->all(FLERR,"Illegal fix nve command");
+
+  dynamic_group_allow = 1;
+  time_integrate = 1;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixNVE2::setmask()
+{
+  int mask = 0;
+  mask |= INITIAL_INTEGRATE;
+  mask |= FINAL_INTEGRATE;
+  mask |= INITIAL_INTEGRATE_RESPA;
+  mask |= FINAL_INTEGRATE_RESPA;
+  return mask;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixNVE2::init()
+{
+  dtv = update->dt;
+  dtf = 0.5 * update->dt * force->ftm2v;
+
+  if (strstr(update->integrate_style,"respa"))
+    step_respa = ((Respa *) update->integrate)->step;
+}
+
+/* ----------------------------------------------------------------------
+   allow for both per-type and per-atom mass
+------------------------------------------------------------------------- */
+
+void FixNVE2::initial_integrate(int /*vflag*/)
+{
+  double dtfm;
+
+  // update v and x of atoms in group
+
+  double **x = atom->x;
+  double **v = atom->v;
+  double **f = atom->f;
+  double *rmass = atom->rmass;
+  double *mass = atom->mass;
+  int *type = atom->type;
+  int *mask = atom->mask;
+  int nlocal = atom->nlocal;
+  if (igroup == atom->firstgroup) nlocal = atom->nfirst;
+
+  if (rmass) {
+    for (int i = 0; i < nlocal; i++)
+      if (mask[i] & groupbit) {
+        dtfm = dtf / rmass[i];
+        v[i][0] += dtfm * f[i][0];
+        v[i][1] += dtfm * f[i][1];
+        v[i][2] += dtfm * f[i][2];
+        x[i][0] += dtv * v[i][0];
+        x[i][1] += dtv * v[i][1];
+        x[i][2] += dtv * v[i][2];
+      }
+
+  } else {
+    for (int i = 0; i < nlocal; i++)
+      if (mask[i] & groupbit) {
+        dtfm = dtf / mass[type[i]];
+        v[i][0] += dtfm * f[i][0];
+        v[i][1] += dtfm * f[i][1];
+        v[i][2] += dtfm * f[i][2];
+        x[i][0] += dtv * v[i][0];
+        x[i][1] += dtv * v[i][1];
+        x[i][2] += dtv * v[i][2];
+      }
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixNVE2::final_integrate()
+{
+  double dtfm;
+
+  // update v of atoms in group
+
+  double **v = atom->v;
+  double **f = atom->f;
+  double *rmass = atom->rmass;
+  double *mass = atom->mass;
+  int *type = atom->type;
+  int *mask = atom->mask;
+  int nlocal = atom->nlocal;
+  if (igroup == atom->firstgroup) nlocal = atom->nfirst;
+
+  if (rmass) {
+    for (int i = 0; i < nlocal; i++)
+      if (mask[i] & groupbit) {
+        dtfm = dtf / rmass[i];
+        v[i][0] += dtfm * f[i][0];
+        v[i][1] += dtfm * f[i][1];
+        v[i][2] += dtfm * f[i][2];
+      }
+
+  } else {
+    for (int i = 0; i < nlocal; i++)
+      if (mask[i] & groupbit) {
+        dtfm = dtf / mass[type[i]];
+        v[i][0] += dtfm * f[i][0];
+        v[i][1] += dtfm * f[i][1];
+        v[i][2] += dtfm * f[i][2];
+      }
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixNVE2::initial_integrate_respa(int vflag, int ilevel, int /*iloop*/)
+{
+  dtv = step_respa[ilevel];
+  dtf = 0.5 * step_respa[ilevel] * force->ftm2v;
+
+  // innermost level - NVE update of v and x
+  // all other levels - NVE update of v
+
+  if (ilevel == 0) initial_integrate(vflag);
+  else final_integrate();
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixNVE2::final_integrate_respa(int ilevel, int /*iloop*/)
+{
+  dtf = 0.5 * step_respa[ilevel] * force->ftm2v;
+  final_integrate();
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixNVE2::reset_dt()
+{
+  dtv = update->dt;
+  dtf = 0.5 * update->dt * force->ftm2v;
+}