From 4f5e9b3c2450125964007a5b0dc81181f64171e5 Mon Sep 17 00:00:00 2001
From: sjplimp <sjplimp@f3b2605a-c512-4ea7-a41b-209d697bcdaa>
Date: Fri, 4 Dec 2009 00:35:23 +0000
Subject: [PATCH] git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@3500
 f3b2605a-c512-4ea7-a41b-209d697bcdaa

---
 src/compute_com.cpp | 56 +++++++++++++++++++++++++++++++++++++++++++++
 src/compute_com.h   | 34 +++++++++++++++++++++++++++
 src/style.h         |  2 ++
 3 files changed, 92 insertions(+)
 create mode 100644 src/compute_com.cpp
 create mode 100644 src/compute_com.h

diff --git a/src/compute_com.cpp b/src/compute_com.cpp
new file mode 100644
index 0000000000..62e08cec6b
--- /dev/null
+++ b/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);
+}
diff --git a/src/compute_com.h b/src/compute_com.h
new file mode 100644
index 0000000000..d07254465c
--- /dev/null
+++ b/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
diff --git a/src/style.h b/src/style.h
index fb7e3cf016..e869920a85 100644
--- a/src/style.h
+++ b/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)