git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@3502 f3b2605a-c512-4ea7-a41b-209d697bcdaa

src/compute_gyration.cpp

@@ -0,0 +1,49 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://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 "compute_gyration.h"
+#include "update.h"
+#include "group.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+
+/* ---------------------------------------------------------------------- */
+
+ComputeGyration::ComputeGyration(LAMMPS *lmp, int narg, char **arg) :
+  Compute(lmp, narg, arg)
+{
+  if (narg != 3) error->all("Illegal compute gyration command");
+
+  scalar_flag = 1;
+  extscalar = 0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void ComputeGyration::init()
+{
+  masstotal = group->mass(igroup);
+}
+
+/* ---------------------------------------------------------------------- */
+
+double ComputeGyration::compute_scalar()
+{
+  invoked_scalar = update->ntimestep;
+
+  double xcm[3];
+  group->xcm(igroup,masstotal,xcm);
+  scalar = group->gyration(igroup,masstotal,xcm);
+  return scalar;
+}

src/compute_gyration.h

@@ -0,0 +1,34 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://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.
+------------------------------------------------------------------------- */
+
+#ifndef COMPUTE_GYRATION_H
+#define COMPUTE_GYRATION_H
+
+#include "compute.h"
+
+namespace LAMMPS_NS {
+
+class ComputeGyration : public Compute {
+ public:
+  ComputeGyration(class LAMMPS *, int, char **);
+  ~ComputeGyration() {}
+  void init();
+  double compute_scalar();
+
+ private:
+  double masstotal;
+};
+
+}
+
+#endif

src/style.h

@@ -82,6 +82,7 @@ CommandStyle(write_restart,WriteRestart)
 #include "compute_coord_atom.h"
 #include "compute_displace_atom.h"
 #include "compute_group_group.h"
+#include "compute_gyration.h"
 #include "compute_heat_flux.h"
 #include "compute_ke.h"
 #include "compute_ke_atom.h"
@@ -110,6 +111,7 @@ ComputeStyle(com,ComputeCOM)
 ComputeStyle(coord/atom,ComputeCoordAtom)
 ComputeStyle(displace/atom,ComputeDisplaceAtom)
 ComputeStyle(group/group,ComputeGroupGroup)
+ComputeStyle(gyration,ComputeGyration)
 ComputeStyle(heat/flux,ComputeHeatFlux)
 ComputeStyle(ke,ComputeKE)
 ComputeStyle(ke/atom,ComputeKEAtom)