git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@3500 f3b2605a-c512-4ea7-a41b-209d697bcdaa

src/compute_com.cpp

@@ -0,0 +1,56 @@
+/* ----------------------------------------------------------------------
+   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_com.h"
+#include "update.h"
+#include "group.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+
+/* ---------------------------------------------------------------------- */
+
+ComputeCOM::ComputeCOM(LAMMPS *lmp, int narg, char **arg) :
+  Compute(lmp, narg, arg)
+{
+  if (narg != 3) error->all("Illegal compute msd command");
+
+  vector_flag = 1;
+  size_vector = 3;
+  extvector = 0;
+
+  vector = new double[3];
+}
+
+/* ---------------------------------------------------------------------- */
+
+ComputeCOM::~ComputeCOM()
+{
+  delete [] vector;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void ComputeCOM::init()
+{
+  masstotal = group->mass(igroup);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void ComputeCOM::compute_vector()
+{
+  invoked_vector = update->ntimestep;
+
+  group->xcm(igroup,masstotal,vector);
+}

src/compute_com.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_COM_H
+#define COMPUTE_COM_H
+
+#include "compute.h"
+
+namespace LAMMPS_NS {
+
+class ComputeCOM : public Compute {
+ public:
+  ComputeCOM(class LAMMPS *, int, char **);
+  ~ComputeCOM();
+  void init();
+  void compute_vector();
+
+ private:
+  double masstotal;
+};
+
+}
+
+#endif

src/style.h

@@ -78,6 +78,7 @@ CommandStyle(write_restart,WriteRestart)
 #ifdef ComputeInclude
 #include "compute_centro_atom.h"
 #include "compute_cna_atom.h"
+#include "compute_com.h"
 #include "compute_coord_atom.h"
 #include "compute_displace_atom.h"
 #include "compute_group_group.h"
@@ -105,6 +106,7 @@ CommandStyle(write_restart,WriteRestart)
 #ifdef ComputeClass
 ComputeStyle(centro/atom,ComputeCentroAtom)
 ComputeStyle(cna/atom,ComputeCNAAtom)
+ComputeStyle(com,ComputeCOM)
 ComputeStyle(coord/atom,ComputeCoordAtom)
 ComputeStyle(displace/atom,ComputeDisplaceAtom)
 ComputeStyle(group/group,ComputeGroupGroup)