diff --git a/src/compute_erotate_sphere_atom.cpp b/src/compute_erotate_sphere_atom.cpp
new file mode 100644
index 0000000000..c058a5eb58
--- /dev/null
+++ b/src/compute_erotate_sphere_atom.cpp
@@ -0,0 +1,110 @@
+/* ----------------------------------------------------------------------
+   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 "string.h"
+#include "compute_erotate_sphere_atom.h"
+#include "atom.h"
+#include "update.h"
+#include "modify.h"
+#include "comm.h"
+#include "force.h"
+#include "memory.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+
+#define INERTIA 0.4          // moment of inertia prefactor for sphere
+
+/* ---------------------------------------------------------------------- */
+
+ComputeErotateSphereAtom::
+ComputeErotateSphereAtom(LAMMPS *lmp, int narg, char **arg) :
+  Compute(lmp, narg, arg)
+{
+  if (narg != 3) 
+    error->all(FLERR,"Illegal compute erotate/sphere//atom command");
+
+  peratom_flag = 1;
+  size_peratom_cols = 0;
+
+  // error check
+
+  if (!atom->sphere_flag)
+    error->all(FLERR,"Compute erotate/sphere/atom requires atom style sphere");
+
+  nmax = 0;
+  erot = NULL;
+}
+
+/* ---------------------------------------------------------------------- */
+
+ComputeErotateSphereAtom::~ComputeErotateSphereAtom()
+{
+  memory->destroy(erot);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void ComputeErotateSphereAtom::init()
+{
+  int count = 0;
+  for (int i = 0; i < modify->ncompute; i++)
+    if (strcmp(modify->compute[i]->style,"erotate/sphere/atom") == 0) count++;
+  if (count > 1 && comm->me == 0)
+    error->warning(FLERR,"More than one compute erotate/sphere/atom");
+
+  pfactor = 0.5 * force->mvv2e * INERTIA;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void ComputeErotateSphereAtom::compute_peratom()
+{
+  invoked_peratom = update->ntimestep;
+
+  // grow erot array if necessary
+
+  if (atom->nlocal > nmax) {
+    memory->destroy(erot);
+    nmax = atom->nmax;
+    memory->create(erot,nmax,"erotate/sphere/atom:erot");
+    vector_atom = erot;
+  }
+
+  // compute rotational kinetic energy for each atom in group
+  // point particles will have erot = 0.0, due to radius = 0.0
+
+  double **omega = atom->omega;
+  double *radius = atom->radius;
+  double *rmass = atom->rmass;
+  int *mask = atom->mask;
+  int nlocal = atom->nlocal;
+
+  for (int i = 0; i < nlocal; i++) {
+    if (mask[i] & groupbit) {
+      erot[i] = (omega[i][0]*omega[i][0] + omega[i][1]*omega[i][1] +
+                 omega[i][2]*omega[i][2]) * radius[i]*radius[i]*rmass[i];
+      erot[i] *= pfactor;
+    } else erot[i] = 0.0;
+  }
+}
+
+/* ----------------------------------------------------------------------
+   memory usage of local atom-based array
+------------------------------------------------------------------------- */
+
+double ComputeErotateSphereAtom::memory_usage()
+{
+  double bytes = nmax * sizeof(double);
+  return bytes;
+}
diff --git a/src/compute_erotate_sphere_atom.h b/src/compute_erotate_sphere_atom.h
new file mode 100644
index 0000000000..b7c775ae11
--- /dev/null
+++ b/src/compute_erotate_sphere_atom.h
@@ -0,0 +1,58 @@
+/* ----------------------------------------------------------------------
+   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.
+------------------------------------------------------------------------- */
+
+#ifdef COMPUTE_CLASS
+
+ComputeStyle(erotate/sphere/atom,ComputeErotateSphereAtom)
+
+#else
+
+#ifndef LMP_COMPUTE_EROTATE_SPHERE_ATOM_H
+#define LMP_COMPUTE_EROTATE_SPHERE_ATOM_H
+
+#include "compute.h"
+
+namespace LAMMPS_NS {
+
+class ComputeErotateSphereAtom : public Compute {
+ public:
+  ComputeErotateSphereAtom(class LAMMPS *, int, char **);
+  ~ComputeErotateSphereAtom();
+  void init();
+  void compute_peratom();
+  double memory_usage();
+
+ private:
+  int nmax;
+  double pfactor;
+  double *erot;
+};
+
+}
+
+#endif
+#endif
+
+/* ERROR/WARNING messages:
+
+E: Illegal ... command
+
+Self-explanatory.  Check the input script syntax and compare to the
+documentation for the command.  You can use -echo screen as a
+command-line option when running LAMMPS to see the offending line.
+
+W: More than one compute erorate/sphere/atom
+
+It is not efficient to use compute erorate/sphere/atom more than once.
+
+*/