diff --git a/src/atom_vec_line.cpp b/src/atom_vec_line.cpp
new file mode 100644
index 0000000000..ebf8b7d7a8
--- /dev/null
+++ b/src/atom_vec_line.cpp
@@ -0,0 +1,1167 @@
+/* ----------------------------------------------------------------------
+   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 "lmptype.h"
+#include "math.h"
+#include "stdlib.h"
+#include "string.h"
+#include "atom_vec_line.h"
+#include "atom.h"
+#include "domain.h"
+#include "modify.h"
+#include "force.h"
+#include "fix.h"
+#include "memory.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+
+#define DELTA 10000
+#define DELTA_BONUS 10000
+#define EPSILON 0.001
+
+/* ---------------------------------------------------------------------- */
+
+AtomVecLine::AtomVecLine(LAMMPS *lmp, int narg, char **arg) :
+  AtomVec(lmp, narg, arg)
+{
+  molecular = 0;
+
+  comm_x_only = comm_f_only = 0;
+  size_forward = 4;
+  size_reverse = 6;
+  size_border = 10;
+  size_velocity = 6;
+  size_data_atom = 8;
+  size_data_vel = 7;
+  size_data_bonus = 5;
+  xcol_data = 6;
+
+  atom->line_flag = 1;
+  atom->molecule_flag = atom->rmass_flag = 1;
+  atom->omega_flag = atom->torque_flag = 1;
+
+  nlocal_bonus = nghost_bonus = nmax_bonus = 0;
+  bonus = NULL;
+}
+
+/* ---------------------------------------------------------------------- */
+
+AtomVecLine::~AtomVecLine()
+{
+  memory->sfree(bonus);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecLine::init()
+{
+  AtomVec::init();
+
+  if (domain->dimension != 2)
+    error->all(FLERR,"Atom_style line can only be used in 2d simulations");
+}
+
+/* ----------------------------------------------------------------------
+   grow atom arrays
+   n = 0 grows arrays by DELTA
+   n > 0 allocates arrays to size n
+------------------------------------------------------------------------- */
+
+void AtomVecLine::grow(int n)
+{
+  if (n == 0) nmax += DELTA;
+  else nmax = n;
+  atom->nmax = nmax;
+
+  tag = memory->grow(atom->tag,nmax,"atom:tag");
+  type = memory->grow(atom->type,nmax,"atom:type");
+  mask = memory->grow(atom->mask,nmax,"atom:mask");
+  image = memory->grow(atom->image,nmax,"atom:image");
+  x = memory->grow(atom->x,nmax,3,"atom:x");
+  v = memory->grow(atom->v,nmax,3,"atom:v");
+  f = memory->grow(atom->f,nmax,3,"atom:f");
+
+  molecule = memory->grow(atom->molecule,nmax,"atom:molecule");
+  rmass = memory->grow(atom->rmass,nmax,"atom:rmass");
+  omega = memory->grow(atom->omega,nmax,3,"atom:omega");
+  torque = memory->grow(atom->torque,nmax,3,"atom:torque");
+  line = memory->grow(atom->line,nmax,"atom:line");
+
+  if (atom->nextra_grow)
+    for (int iextra = 0; iextra < atom->nextra_grow; iextra++)
+      modify->fix[atom->extra_grow[iextra]]->grow_arrays(nmax);
+}
+
+/* ----------------------------------------------------------------------
+   reset local array ptrs
+------------------------------------------------------------------------- */
+
+void AtomVecLine::grow_reset()
+{
+  tag = atom->tag; type = atom->type;
+  mask = atom->mask; image = atom->image;
+  x = atom->x; v = atom->v; f = atom->f;
+  molecule = atom->molecule; rmass = atom->rmass;
+  omega = atom->omega; torque = atom->torque;
+}
+
+/* ----------------------------------------------------------------------
+   grow bonus data structure
+------------------------------------------------------------------------- */
+
+void AtomVecLine::grow_bonus()
+{
+  nmax_bonus += DELTA_BONUS;
+  if (nmax_bonus < 0 || nmax_bonus > MAXSMALLINT)
+    error->one(FLERR,"Per-processor system is too big");
+
+  bonus = (Bonus *) memory->srealloc(bonus,nmax_bonus*sizeof(Bonus),
+				     "atom:bonus");
+}
+
+/* ----------------------------------------------------------------------
+   copy atom I info to atom J
+------------------------------------------------------------------------- */
+
+void AtomVecLine::copy(int i, int j, int delflag)
+{
+  tag[j] = tag[i];
+  type[j] = type[i];
+  mask[j] = mask[i];
+  image[j] = image[i];
+  x[j][0] = x[i][0];
+  x[j][1] = x[i][1];
+  x[j][2] = x[i][2];
+  v[j][0] = v[i][0];
+  v[j][1] = v[i][1];
+  v[j][2] = v[i][2];
+
+  molecule[j] = molecule[i];
+  rmass[j] = rmass[i];
+  omega[j][0] = omega[i][0];
+  omega[j][1] = omega[i][1];
+  omega[j][2] = omega[i][2];
+
+  // if delflag and atom J has bonus data, then delete it
+
+  if (delflag && line[j] >= 0) {
+    copy_bonus(nlocal_bonus-1,line[j]);
+    nlocal_bonus--;
+  }
+
+  // if atom I has bonus data and not deleting I, repoint I's bonus to J
+
+  if (line[i] >= 0 && i != j) bonus[line[i]].ilocal = j;
+  line[j] = line[i];
+
+  if (atom->nextra_grow)
+    for (int iextra = 0; iextra < atom->nextra_grow; iextra++)
+      modify->fix[atom->extra_grow[iextra]]->copy_arrays(i,j);
+}
+
+/* ----------------------------------------------------------------------
+   copy bonus data from I to J, effectively deleting the J entry
+   insure index pointers between per-atom and bonus data are updated
+------------------------------------------------------------------------- */
+
+void AtomVecLine::copy_bonus(int i, int j)
+{
+  memcpy(&bonus[j],&bonus[i],sizeof(Bonus));
+  line[bonus[j].ilocal] = j;
+}
+
+/* ----------------------------------------------------------------------
+   clear ghost info in bonus data
+   called before ghosts are recommunicated in comm and irregular
+------------------------------------------------------------------------- */
+
+void AtomVecLine::clear_bonus()
+{
+  nghost_bonus = 0;
+}
+
+/* ----------------------------------------------------------------------
+   set length value in bonus data for particle I
+   oriented along x axis
+   this may create or delete entry in bonus data
+------------------------------------------------------------------------- */
+
+void AtomVecLine::set_length(int i, double value) 
+{
+  if (line[i] < 0) {
+    if (value == 0.0) return;
+    if (nlocal_bonus == nmax_bonus) grow_bonus();
+    bonus[nlocal_bonus].length = value;
+    bonus[nlocal_bonus].theta = 0.0;
+    bonus[nlocal_bonus].ilocal = i;
+    line[i] = nlocal_bonus++;
+  } else if (value == 0.0) {
+    copy_bonus(nlocal_bonus-1,line[i]);
+    nlocal_bonus--;
+    line[i] = -1;
+  } else bonus[line[i]].length = value;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::pack_comm(int n, int *list, double *buf,
+			   int pbc_flag, int *pbc)
+{
+  int i,j,m;
+  double dx,dy,dz;
+
+  m = 0;
+  if (pbc_flag == 0) {
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0];
+      buf[m++] = x[j][1];
+      buf[m++] = x[j][2];
+      if (line[j] >= 0) buf[m++] = bonus[line[j]].theta;
+    }
+  } else {
+    if (domain->triclinic == 0) {
+      dx = pbc[0]*domain->xprd;
+      dy = pbc[1]*domain->yprd;
+      dz = pbc[2]*domain->zprd;
+    } else {
+      dx = pbc[0]*domain->xprd + pbc[5]*domain->xy + pbc[4]*domain->xz;
+      dy = pbc[1]*domain->yprd + pbc[3]*domain->yz;
+      dz = pbc[2]*domain->zprd;
+    }
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0] + dx;
+      buf[m++] = x[j][1] + dy;
+      buf[m++] = x[j][2] + dz;
+      if (line[j] >= 0) buf[m++] = bonus[line[j]].theta;
+    }
+  }
+
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::pack_comm_vel(int n, int *list, double *buf,
+			       int pbc_flag, int *pbc)
+{
+  int i,j,m;
+  double dx,dy,dz,dvx,dvy,dvz;
+
+  m = 0;
+  if (pbc_flag == 0) {
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0];
+      buf[m++] = x[j][1];
+      buf[m++] = x[j][2];
+      if (line[j] >= 0) buf[m++] = bonus[line[j]].theta;
+      buf[m++] = v[j][0];
+      buf[m++] = v[j][1];
+      buf[m++] = v[j][2];
+      buf[m++] = omega[j][0];
+      buf[m++] = omega[j][1];
+      buf[m++] = omega[j][2];
+    }
+  } else {
+    if (domain->triclinic == 0) {
+      dx = pbc[0]*domain->xprd;
+      dy = pbc[1]*domain->yprd;
+      dz = pbc[2]*domain->zprd;
+    } else {
+      dx = pbc[0]*domain->xprd + pbc[5]*domain->xy + pbc[4]*domain->xz;
+      dy = pbc[1]*domain->yprd + pbc[3]*domain->yz;
+      dz = pbc[2]*domain->zprd;
+    }
+    if (!deform_vremap) {
+      for (i = 0; i < n; i++) {
+	j = list[i];
+	buf[m++] = x[j][0] + dx;
+	buf[m++] = x[j][1] + dy;
+	buf[m++] = x[j][2] + dz;
+	if (line[j] >= 0) buf[m++] = bonus[line[j]].theta;
+	buf[m++] = v[j][0];
+	buf[m++] = v[j][1];
+	buf[m++] = v[j][2];
+	buf[m++] = omega[j][0];
+	buf[m++] = omega[j][1];
+	buf[m++] = omega[j][2];
+      }
+    } else {
+      dvx = pbc[0]*h_rate[0] + pbc[5]*h_rate[5] + pbc[4]*h_rate[4];
+      dvy = pbc[1]*h_rate[1] + pbc[3]*h_rate[3];
+      dvz = pbc[2]*h_rate[2];
+      for (i = 0; i < n; i++) {
+	j = list[i];
+	buf[m++] = x[j][0] + dx;
+	buf[m++] = x[j][1] + dy;
+	buf[m++] = x[j][2] + dz;
+	if (line[j] >= 0) buf[m++] = bonus[line[j]].theta;
+	if (mask[i] & deform_groupbit) {
+	  buf[m++] = v[j][0] + dvx;
+	  buf[m++] = v[j][1] + dvy;
+	  buf[m++] = v[j][2] + dvz;
+	} else {
+	  buf[m++] = v[j][0];
+	  buf[m++] = v[j][1];
+	  buf[m++] = v[j][2];
+	}
+	buf[m++] = omega[j][0];
+	buf[m++] = omega[j][1];
+	buf[m++] = omega[j][2];
+      }
+    }
+  }
+
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::pack_comm_hybrid(int n, int *list, double *buf)
+{
+  int i,j,m;
+
+  m = 0;
+  for (i = 0; i < n; i++) {
+    j = list[i];
+    if (line[j] >= 0) buf[m++] = bonus[line[j]].theta;
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecLine::unpack_comm(int n, int first, double *buf)
+{
+  int i,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    x[i][0] = buf[m++];
+    x[i][1] = buf[m++];
+    x[i][2] = buf[m++];
+    if (line[i] >= 0) bonus[line[i]].theta = buf[m++];
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecLine::unpack_comm_vel(int n, int first, double *buf)
+{
+  int i,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    x[i][0] = buf[m++];
+    x[i][1] = buf[m++];
+    x[i][2] = buf[m++];
+    if (line[i] >= 0) bonus[line[i]].theta = buf[m++];
+    v[i][0] = buf[m++];
+    v[i][1] = buf[m++];
+    v[i][2] = buf[m++];
+    omega[i][0] = buf[m++];
+    omega[i][1] = buf[m++];
+    omega[i][2] = buf[m++];
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::unpack_comm_hybrid(int n, int first, double *buf)
+{
+  int i,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++)
+    if (line[i] >= 0) bonus[line[i]].theta = buf[m++];
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::pack_reverse(int n, int first, double *buf)
+{
+  int i,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    buf[m++] = f[i][0];
+    buf[m++] = f[i][1];
+    buf[m++] = f[i][2];
+    buf[m++] = torque[i][0];
+    buf[m++] = torque[i][1];
+    buf[m++] = torque[i][2];
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::pack_reverse_hybrid(int n, int first, double *buf)
+{
+  int i,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    buf[m++] = torque[i][0];
+    buf[m++] = torque[i][1];
+    buf[m++] = torque[i][2];
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecLine::unpack_reverse(int n, int *list, double *buf)
+{
+  int i,j,m;
+
+  m = 0;
+  for (i = 0; i < n; i++) {
+    j = list[i];
+    f[j][0] += buf[m++];
+    f[j][1] += buf[m++];
+    f[j][2] += buf[m++];
+    torque[j][0] += buf[m++];
+    torque[j][1] += buf[m++];
+    torque[j][2] += buf[m++];
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::unpack_reverse_hybrid(int n, int *list, double *buf)
+{
+  int i,j,m;
+
+  m = 0;
+  for (i = 0; i < n; i++) {
+    j = list[i];
+    torque[j][0] += buf[m++];
+    torque[j][1] += buf[m++];
+    torque[j][2] += buf[m++];
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::pack_border(int n, int *list, double *buf,
+			     int pbc_flag, int *pbc)
+{
+  int i,j,m;
+  double dx,dy,dz;
+
+  m = 0;
+  if (pbc_flag == 0) {
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0];
+      buf[m++] = x[j][1];
+      buf[m++] = x[j][2];
+      buf[m++] = tag[j];
+      buf[m++] = type[j];
+      buf[m++] = mask[j];
+      buf[m++] = molecule[j];
+      if (line[j] < 0) buf[m++] = 0;
+      else {
+	buf[m++] = 1;
+	buf[m++] = bonus[line[j]].length;
+	buf[m++] = bonus[line[j]].theta;
+      }
+    }
+  } else {
+    if (domain->triclinic == 0) {
+      dx = pbc[0]*domain->xprd;
+      dy = pbc[1]*domain->yprd;
+      dz = pbc[2]*domain->zprd;
+    } else {
+      dx = pbc[0];
+      dy = pbc[1];
+      dz = pbc[2];
+    }
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0] + dx;
+      buf[m++] = x[j][1] + dy;
+      buf[m++] = x[j][2] + dz;
+      buf[m++] = tag[j];
+      buf[m++] = type[j];
+      buf[m++] = mask[j];
+      buf[m++] = molecule[j];
+      if (line[j] < 0) buf[m++] = 0;
+      else {
+	buf[m++] = 1;
+	buf[m++] = bonus[line[j]].length;
+	buf[m++] = bonus[line[j]].theta;
+      }
+    }
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::pack_border_vel(int n, int *list, double *buf,
+				 int pbc_flag, int *pbc)
+{
+  int i,j,m;
+  double dx,dy,dz,dvx,dvy,dvz;
+
+  m = 0;
+  if (pbc_flag == 0) {
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0];
+      buf[m++] = x[j][1];
+      buf[m++] = x[j][2];
+      buf[m++] = tag[j];
+      buf[m++] = type[j];
+      buf[m++] = mask[j];
+      buf[m++] = molecule[j];
+      if (line[j] < 0) buf[m++] = 0;
+      else {
+	buf[m++] = 1;
+	buf[m++] = bonus[line[j]].length;
+	buf[m++] = bonus[line[j]].theta;
+      }
+      buf[m++] = v[j][0];
+      buf[m++] = v[j][1];
+      buf[m++] = v[j][2];
+      buf[m++] = omega[j][0];
+      buf[m++] = omega[j][1];
+      buf[m++] = omega[j][2];
+    }
+  } else {
+    if (domain->triclinic == 0) {
+      dx = pbc[0]*domain->xprd;
+      dy = pbc[1]*domain->yprd;
+      dz = pbc[2]*domain->zprd;
+    } else {
+      dx = pbc[0];
+      dy = pbc[1];
+      dz = pbc[2];
+    }
+    if (!deform_vremap) {
+      for (i = 0; i < n; i++) {
+	j = list[i];
+	buf[m++] = x[j][0] + dx;
+	buf[m++] = x[j][1] + dy;
+	buf[m++] = x[j][2] + dz;
+	buf[m++] = tag[j];
+	buf[m++] = type[j];
+	buf[m++] = mask[j];
+	buf[m++] = molecule[j];
+	if (line[j] < 0) buf[m++] = 0;
+	else {
+	  buf[m++] = 1;
+	  buf[m++] = bonus[line[j]].length;
+	  buf[m++] = bonus[line[j]].theta;
+	}
+	buf[m++] = v[j][0];
+	buf[m++] = v[j][1];
+	buf[m++] = v[j][2];
+	buf[m++] = omega[j][0];
+	buf[m++] = omega[j][1];
+	buf[m++] = omega[j][2];
+      }
+    } else {
+      dvx = pbc[0]*h_rate[0] + pbc[5]*h_rate[5] + pbc[4]*h_rate[4];
+      dvy = pbc[1]*h_rate[1] + pbc[3]*h_rate[3];
+      dvz = pbc[2]*h_rate[2];
+      for (i = 0; i < n; i++) {
+	j = list[i];
+	buf[m++] = x[j][0] + dx;
+	buf[m++] = x[j][1] + dy;
+	buf[m++] = x[j][2] + dz;
+	buf[m++] = tag[j];
+	buf[m++] = type[j];
+	buf[m++] = mask[j];
+	buf[m++] = molecule[j];
+	if (line[j] < 0) buf[m++] = 0;
+	else {
+	  buf[m++] = 1;
+	  buf[m++] = bonus[line[j]].length;
+	  buf[m++] = bonus[line[j]].theta;
+	}
+	if (mask[i] & deform_groupbit) {
+	  buf[m++] = v[j][0] + dvx;
+	  buf[m++] = v[j][1] + dvy;
+	  buf[m++] = v[j][2] + dvz;
+	} else {
+	  buf[m++] = v[j][0];
+	  buf[m++] = v[j][1];
+	  buf[m++] = v[j][2];
+	}
+	buf[m++] = omega[j][0];
+	buf[m++] = omega[j][1];
+	buf[m++] = omega[j][2];
+      }
+    }
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::pack_border_hybrid(int n, int *list, double *buf)
+{
+  int i,j,m;
+
+  m = 0;
+  for (i = 0; i < n; i++) {
+    j = list[i];
+    buf[m++] = molecule[j];
+    if (line[j] < 0) buf[m++] = 0;
+    else {
+      buf[m++] = 1;
+      buf[m++] = bonus[line[j]].length;
+      buf[m++] = bonus[line[j]].theta;
+    }
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecLine::unpack_border(int n, int first, double *buf)
+{
+  int i,j,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    if (i == nmax) grow(0);
+    x[i][0] = buf[m++];
+    x[i][1] = buf[m++];
+    x[i][2] = buf[m++];
+    tag[i] = static_cast<int> (buf[m++]);
+    type[i] = static_cast<int> (buf[m++]);
+    mask[i] = static_cast<int> (buf[m++]);
+    molecule[i] = static_cast<int> (buf[m++]);
+    line[i] = static_cast<int> (buf[m++]);
+    if (line[i] == 0) line[i] = -1;
+    else {
+      j = nlocal_bonus + nghost_bonus;
+      if (j == nmax_bonus) grow_bonus();
+      bonus[j].length = buf[m++];
+      bonus[j].theta = buf[m++];
+      bonus[j].ilocal = i;
+      line[i] = j;
+      nghost_bonus++;
+    }
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecLine::unpack_border_vel(int n, int first, double *buf)
+{
+  int i,j,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    if (i == nmax) grow(0);
+    x[i][0] = buf[m++];
+    x[i][1] = buf[m++];
+    x[i][2] = buf[m++];
+    tag[i] = static_cast<int> (buf[m++]);
+    type[i] = static_cast<int> (buf[m++]);
+    mask[i] = static_cast<int> (buf[m++]);
+    molecule[i] = static_cast<int> (buf[m++]);
+    line[i] = static_cast<int> (buf[m++]);
+    if (line[i] == 0) line[i] = -1;
+    else {
+      j = nlocal_bonus + nghost_bonus;
+      if (j == nmax_bonus) grow_bonus();
+      bonus[j].length = buf[m++];
+      bonus[j].theta = buf[m++];
+      bonus[j].ilocal = i;
+      line[i] = j;
+      nghost_bonus++;
+    }
+    v[i][0] = buf[m++];
+    v[i][1] = buf[m++];
+    v[i][2] = buf[m++];
+    omega[i][0] = buf[m++];
+    omega[i][1] = buf[m++];
+    omega[i][2] = buf[m++];
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::unpack_border_hybrid(int n, int first, double *buf)
+{
+  int i,j,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    molecule[i] = static_cast<int> (buf[m++]);
+    line[i] = static_cast<int> (buf[m++]);
+    if (line[i] == 0) line[i] = -1;
+    else {
+      j = nlocal_bonus + nghost_bonus;
+      if (j == nmax_bonus) grow_bonus();
+      bonus[j].length = buf[m++];
+      bonus[j].theta = buf[m++];
+      bonus[j].ilocal = i;
+      line[i] = j;
+      nghost_bonus++;
+    }
+  }
+  return m;
+}
+
+/* ----------------------------------------------------------------------
+   pack data for atom I for sending to another proc
+   xyz must be 1st 3 values, so comm::exchange() can test on them 
+------------------------------------------------------------------------- */
+
+int AtomVecLine::pack_exchange(int i, double *buf)
+{
+  int m = 1;
+  buf[m++] = x[i][0];
+  buf[m++] = x[i][1];
+  buf[m++] = x[i][2];
+  buf[m++] = v[i][0];
+  buf[m++] = v[i][1];
+  buf[m++] = v[i][2];
+  buf[m++] = tag[i];
+  buf[m++] = type[i];
+  buf[m++] = mask[i];
+  buf[m++] = image[i];
+
+  buf[m++] = molecule[i];
+  buf[m++] = rmass[i];
+  buf[m++] = omega[i][0];
+  buf[m++] = omega[i][1];
+  buf[m++] = omega[i][2];
+
+  if (line[i] < 0) buf[m++] = 0;
+  else {
+    buf[m++] = 1;
+    int j = line[i];
+    buf[m++] = bonus[j].length;
+    buf[m++] = bonus[j].theta;
+  }
+
+  if (atom->nextra_grow)
+    for (int iextra = 0; iextra < atom->nextra_grow; iextra++) 
+      m += modify->fix[atom->extra_grow[iextra]]->pack_exchange(i,&buf[m]);
+
+  buf[0] = m;
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecLine::unpack_exchange(double *buf)
+{
+  int nlocal = atom->nlocal;
+  if (nlocal == nmax) grow(0);
+
+  int m = 1;
+  x[nlocal][0] = buf[m++];
+  x[nlocal][1] = buf[m++];
+  x[nlocal][2] = buf[m++];
+  v[nlocal][0] = buf[m++];
+  v[nlocal][1] = buf[m++];
+  v[nlocal][2] = buf[m++];
+  tag[nlocal] = static_cast<int> (buf[m++]);
+  type[nlocal] = static_cast<int> (buf[m++]);
+  mask[nlocal] = static_cast<int> (buf[m++]);
+  image[nlocal] = static_cast<int> (buf[m++]);
+
+  molecule[nlocal] = static_cast<int> (buf[m++]);
+  rmass[nlocal] = buf[m++];
+  omega[nlocal][0] = buf[m++];
+  omega[nlocal][1] = buf[m++];
+  omega[nlocal][2] = buf[m++];
+
+  line[nlocal] = static_cast<int> (buf[m++]);
+  if (line[nlocal] == 0) line[nlocal] = -1;
+  else {
+    if (nlocal_bonus == nmax_bonus) grow_bonus();
+    bonus[nlocal_bonus].length = buf[m++];
+    bonus[nlocal_bonus].theta = buf[m++];
+    bonus[nlocal_bonus].ilocal = nlocal;
+    line[nlocal] = nlocal_bonus++;
+  }
+
+  if (atom->nextra_grow)
+    for (int iextra = 0; iextra < atom->nextra_grow; iextra++) 
+      m += modify->fix[atom->extra_grow[iextra]]->
+	unpack_exchange(nlocal,&buf[m]);
+
+  atom->nlocal++;
+  return m;
+}
+
+/* ----------------------------------------------------------------------
+   size of restart data for all atoms owned by this proc
+   include extra data stored by fixes
+------------------------------------------------------------------------- */
+
+int AtomVecLine::size_restart()
+{
+  int i;
+
+  int n = 0;
+  int nlocal = atom->nlocal;
+  for (i = 0; i < nlocal; i++)
+    if (line[i] >= 0) n += 19;
+    else n += 17;
+
+  if (atom->nextra_restart)
+    for (int iextra = 0; iextra < atom->nextra_restart; iextra++) 
+      for (i = 0; i < nlocal; i++)
+	n += modify->fix[atom->extra_restart[iextra]]->size_restart(i);
+
+  return n;
+}
+
+/* ----------------------------------------------------------------------
+   pack atom I's data for restart file including extra quantities
+   xyz must be 1st 3 values, so that read_restart can test on them
+   molecular types may be negative, but write as positive   
+------------------------------------------------------------------------- */
+
+int AtomVecLine::pack_restart(int i, double *buf)
+{
+  int m = 1;
+  buf[m++] = x[i][0];
+  buf[m++] = x[i][1];
+  buf[m++] = x[i][2];
+  buf[m++] = tag[i];
+  buf[m++] = type[i];
+  buf[m++] = mask[i];
+  buf[m++] = image[i];
+  buf[m++] = v[i][0];
+  buf[m++] = v[i][1];
+  buf[m++] = v[i][2];
+
+  buf[m++] = molecule[i];
+  buf[m++] = rmass[i];
+  buf[m++] = omega[i][0];
+  buf[m++] = omega[i][1];
+  buf[m++] = omega[i][2];
+
+  if (line[i] < 0) buf[m++] = 0;
+  else {
+    buf[m++] = 1;
+    int j = line[i];
+    buf[m++] = bonus[j].length;
+    buf[m++] = bonus[j].theta;
+  }
+
+  if (atom->nextra_restart)
+    for (int iextra = 0; iextra < atom->nextra_restart; iextra++) 
+      m += modify->fix[atom->extra_restart[iextra]]->pack_restart(i,&buf[m]);
+
+  buf[0] = m;
+  return m;
+}
+
+/* ----------------------------------------------------------------------
+   unpack data for one atom from restart file including extra quantities
+------------------------------------------------------------------------- */
+
+int AtomVecLine::unpack_restart(double *buf)
+{
+  int nlocal = atom->nlocal;
+  if (nlocal == nmax) {
+    grow(0);
+    if (atom->nextra_store)
+      memory->grow(atom->extra,nmax,atom->nextra_store,"atom:extra");
+  }
+
+  int m = 1;
+  x[nlocal][0] = buf[m++];
+  x[nlocal][1] = buf[m++];
+  x[nlocal][2] = buf[m++];
+  tag[nlocal] = static_cast<int> (buf[m++]);
+  type[nlocal] = static_cast<int> (buf[m++]);
+  mask[nlocal] = static_cast<int> (buf[m++]);
+  image[nlocal] = static_cast<int> (buf[m++]);
+  v[nlocal][0] = buf[m++];
+  v[nlocal][1] = buf[m++];
+  v[nlocal][2] = buf[m++];
+
+  molecule[nlocal] = static_cast<int> (buf[m++]);
+  rmass[nlocal] = buf[m++];
+  omega[nlocal][0] = buf[m++];
+  omega[nlocal][1] = buf[m++];
+  omega[nlocal][2] = buf[m++];
+
+  line[nlocal] = static_cast<int> (buf[m++]);
+  if (line[nlocal] == 0) line[nlocal] = -1;
+  else {
+    if (nlocal_bonus == nmax_bonus) grow_bonus();
+    bonus[nlocal_bonus].length = buf[m++];
+    bonus[nlocal_bonus].theta = buf[m++];
+    bonus[nlocal_bonus].ilocal = nlocal;
+    line[nlocal] = nlocal_bonus++;
+  }
+
+  double **extra = atom->extra;
+  if (atom->nextra_store) {
+    int size = static_cast<int> (buf[0]) - m;
+    for (int i = 0; i < size; i++) extra[nlocal][i] = buf[m++];
+  }
+
+  atom->nlocal++;
+  return m;
+}
+
+/* ----------------------------------------------------------------------
+   create one atom of itype at coord
+   set other values to defaults
+------------------------------------------------------------------------- */
+
+void AtomVecLine::create_atom(int itype, double *coord)
+{
+  int nlocal = atom->nlocal;
+  if (nlocal == nmax) grow(0);
+
+  tag[nlocal] = 0;
+  type[nlocal] = itype;
+  x[nlocal][0] = coord[0];
+  x[nlocal][1] = coord[1];
+  x[nlocal][2] = coord[2];
+  mask[nlocal] = 1;
+  image[nlocal] = (512 << 20) | (512 << 10) | 512;
+  v[nlocal][0] = 0.0;
+  v[nlocal][1] = 0.0;
+  v[nlocal][2] = 0.0;
+
+  molecule[nlocal] = 0;
+  rmass[nlocal] = 1.0;
+  omega[nlocal][0] = 0.0;
+  omega[nlocal][1] = 0.0;
+  omega[nlocal][2] = 0.0;
+  line[nlocal] = -1;
+
+  atom->nlocal++;
+}
+
+/* ----------------------------------------------------------------------
+   unpack one line from Atoms section of data file
+   initialize other atom quantities
+------------------------------------------------------------------------- */
+
+void AtomVecLine::data_atom(double *coord, int imagetmp, char **values)
+{
+  int nlocal = atom->nlocal;
+  if (nlocal == nmax) grow(0);
+
+  tag[nlocal] = atoi(values[0]);
+  if (tag[nlocal] <= 0)
+    error->one(FLERR,"Invalid atom ID in Atoms section of data file");
+
+  molecule[nlocal] = atoi(values[1]);
+
+  type[nlocal] = atoi(values[2]);
+  if (type[nlocal] <= 0 || type[nlocal] > atom->ntypes)
+    error->one(FLERR,"Invalid atom type in Atoms section of data file");
+
+  line[nlocal] = atoi(values[3]);
+  if (line[nlocal] == 0) line[nlocal] = -1;
+  else if (line[nlocal] == 1) line[nlocal] = 0;
+  else error->one(FLERR,"Invalid atom type in Atoms section of data file");
+
+  rmass[nlocal] = atof(values[4]);
+  if (rmass[nlocal] <= 0.0)
+    error->one(FLERR,"Invalid density in Atoms section of data file");
+
+  x[nlocal][0] = coord[0];
+  x[nlocal][1] = coord[1];
+  x[nlocal][2] = coord[2];
+
+  image[nlocal] = imagetmp;
+
+  mask[nlocal] = 1;
+  v[nlocal][0] = 0.0;
+  v[nlocal][1] = 0.0;
+  v[nlocal][2] = 0.0;
+  omega[nlocal][0] = 0.0;
+  omega[nlocal][1] = 0.0;
+  omega[nlocal][2] = 0.0;
+
+  atom->nlocal++;
+}
+
+/* ----------------------------------------------------------------------
+   unpack hybrid quantities from one line in Atoms section of data file
+   initialize other atom quantities for this sub-style
+------------------------------------------------------------------------- */
+
+int AtomVecLine::data_atom_hybrid(int nlocal, char **values)
+{
+  molecule[nlocal] = atoi(values[0]);
+
+  line[nlocal] = atoi(values[1]);
+  if (line[nlocal] == 0) line[nlocal] = -1;
+  else if (line[nlocal] == 1) line[nlocal] = 0;
+  else error->one(FLERR,"Invalid atom type in Atoms section of data file");
+
+  rmass[nlocal] = atof(values[2]);
+  if (rmass[nlocal] <= 0.0)
+    error->one(FLERR,"Invalid density in Atoms section of data file");
+
+  return 3;
+}
+
+/* ----------------------------------------------------------------------
+   unpack one line from Lines section of data file
+------------------------------------------------------------------------- */
+
+void AtomVecLine::data_atom_bonus(int m, char **values)
+{
+  if (line[m]) error->one(FLERR,"Assigning line parameters to non-line atom");
+
+  if (nlocal_bonus == nmax_bonus) grow_bonus();
+
+  double x1 = atof(values[0]);
+  double y1 = atof(values[1]);
+  double x2 = atof(values[2]);
+  double y2 = atof(values[3]);
+  double dx = x2 - x1;
+  double dy = y2 - y1;
+  double length = sqrt(dx*dx + dy*dy);
+
+  bonus[nlocal_bonus].length = length;
+  if (dy >= 0.0) bonus[nlocal_bonus].theta = acos(dx/length);
+  else bonus[nlocal_bonus].theta = -acos(dx/length);
+
+  double xc = 0.5*(x1+x2);
+  double yc = 0.5*(y1+y2);
+  dx = xc - x[m][0];
+  dy = yc - x[m][1];
+  double delta = sqrt(dx*dx + dy*dy);
+
+  if (delta/length > EPSILON)
+    error->one(FLERR,"Inconsistent line segment in data file");
+
+  x[m][0] = xc;
+  x[m][1] = yc;
+
+  // reset line mass
+  // previously stored density in rmass
+
+  rmass[m] *= length;
+
+  bonus[nlocal_bonus].ilocal = m;
+  line[m] = nlocal_bonus++;
+}
+
+/* ----------------------------------------------------------------------
+   unpack one line from Velocities section of data file
+------------------------------------------------------------------------- */
+
+void AtomVecLine::data_vel(int m, char **values)
+{
+  v[m][0] = atof(values[0]);
+  v[m][1] = atof(values[1]);
+  v[m][2] = atof(values[2]);
+  omega[m][0] = atof(values[3]);
+  omega[m][1] = atof(values[4]);
+  omega[m][2] = atof(values[5]);
+}
+
+/* ----------------------------------------------------------------------
+   unpack hybrid quantities from one line in Velocities section of data file
+------------------------------------------------------------------------- */
+
+int AtomVecLine::data_vel_hybrid(int m, char **values)
+{
+  omega[m][0] = atof(values[0]);
+  omega[m][1] = atof(values[1]);
+  omega[m][2] = atof(values[2]);
+  return 3;
+}
+
+/* ----------------------------------------------------------------------
+   return # of bytes of allocated memory 
+------------------------------------------------------------------------- */
+
+bigint AtomVecLine::memory_usage()
+{
+  bigint bytes = 0;
+
+  if (atom->memcheck("tag")) bytes += memory->usage(tag,nmax);
+  if (atom->memcheck("type")) bytes += memory->usage(type,nmax);
+  if (atom->memcheck("mask")) bytes += memory->usage(mask,nmax);
+  if (atom->memcheck("image")) bytes += memory->usage(image,nmax);
+  if (atom->memcheck("x")) bytes += memory->usage(x,nmax,3);
+  if (atom->memcheck("v")) bytes += memory->usage(v,nmax,3);
+  if (atom->memcheck("f")) bytes += memory->usage(f,nmax,3);
+
+  if (atom->memcheck("molecule")) bytes += memory->usage(molecule,nmax);
+  if (atom->memcheck("rmass")) bytes += memory->usage(rmass,nmax);
+  if (atom->memcheck("omega")) bytes += memory->usage(omega,nmax,3);
+  if (atom->memcheck("torque")) bytes += memory->usage(torque,nmax,3);
+  if (atom->memcheck("line")) bytes += memory->usage(line,nmax);
+
+  bytes += nmax_bonus*sizeof(Bonus);
+
+  return bytes;
+}
+
+/* ----------------------------------------------------------------------
+   check consistency of internal Bonus data structure
+   n = # of atoms in regular structure to check against
+------------------------------------------------------------------------- */
+
+/*
+void AtomVecLine::consistency_check(int n, char *str)
+{
+  int iflag = 0;
+  int count = 0;
+  for (int i = 0; i < n; i++) {
+      
+    if (line[i] >= 0) {
+      count++;
+      if (line[i] >= nlocal_bonus) iflag++;
+      if (bonus[line[i]].ilocal != i) iflag++;
+      //if (comm->me == 1 && update->ntimestep == 873)
+      //	printf("CCHK %s: %d %d: %d %d: %d %d\n",
+      //       str,i,n,line[i],nlocal_bonus,bonus[line[i]].ilocal,iflag);
+    }
+  }
+
+  if (iflag) {
+    char msg[128];
+    sprintf(msg,"BAD VECLINE PTRS: %s: %d %d: %d\n",str,comm->me,
+	    update->ntimestep,iflag);
+    error->one(FLERR,msg);
+  }
+
+  if (count != nlocal_bonus) {
+    char msg[128];
+    sprintf(msg,"BAD VECLINE COUNT: %s: %d %d: %d %d\n",
+	    str,comm->me,update->ntimestep,count,nlocal_bonus);
+    error->one(FLERR,msg);
+  }
+}
+*/
diff --git a/src/atom_vec_line.h b/src/atom_vec_line.h
new file mode 100644
index 0000000000..3dd6d6e37c
--- /dev/null
+++ b/src/atom_vec_line.h
@@ -0,0 +1,96 @@
+/* ----------------------------------------------------------------------
+   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 ATOM_CLASS
+
+AtomStyle(line,AtomVecLine)
+
+#else
+
+#ifndef LMP_ATOM_VEC_LINE_H
+#define LMP_ATOM_VEC_LINE_H
+
+#include "atom_vec.h"
+
+namespace LAMMPS_NS {
+
+class AtomVecLine : public AtomVec {
+ public:
+  struct Bonus {
+    double length,theta;
+    int ilocal;
+  };
+  struct Bonus *bonus;
+
+  AtomVecLine(class LAMMPS *, int, char **);
+  ~AtomVecLine();
+  void init();
+  void grow(int);
+  void grow_reset();
+  void copy(int, int, int);
+  int pack_comm(int, int *, double *, int, int *);
+  int pack_comm_vel(int, int *, double *, int, int *);
+  int pack_comm_hybrid(int, int *, double *);
+  void unpack_comm(int, int, double *);
+  void unpack_comm_vel(int, int, double *);
+  int unpack_comm_hybrid(int, int, double *);
+  int pack_reverse(int, int, double *);
+  int pack_reverse_hybrid(int, int, double *);
+  void unpack_reverse(int, int *, double *);
+  int unpack_reverse_hybrid(int, int *, double *);
+  int pack_border(int, int *, double *, int, int *);
+  int pack_border_vel(int, int *, double *, int, int *);
+  int pack_border_hybrid(int, int *, double *);
+  void unpack_border(int, int, double *);
+  void unpack_border_vel(int, int, double *);
+  int unpack_border_hybrid(int, int, double *);
+  int pack_exchange(int, double *);
+  int unpack_exchange(double *);
+  int size_restart();
+  int pack_restart(int, double *);
+  int unpack_restart(double *);
+  void create_atom(int, double *);
+  void data_atom(double *, int, char **);
+  int data_atom_hybrid(int, char **);
+  void data_vel(int, char **);
+  int data_vel_hybrid(int, char **);
+  bigint memory_usage();
+
+  // manipulate Bonus data structure for extra atom info
+
+  void clear_bonus();
+  void data_atom_bonus(int, char **);
+
+  // unique to AtomVecLine
+
+  void set_length(int, double);
+
+ private:
+  int *tag,*type,*mask,*image;
+  double **x,**v,**f;
+  int *molecule;
+  double *rmass;
+  double **omega,**torque;
+  int *line;
+
+  int nlocal_bonus,nghost_bonus,nmax_bonus;
+
+  void grow_bonus();
+  void copy_bonus(int, int);
+  // void consistency_check(int, char *);
+};
+
+}
+
+#endif
+#endif
diff --git a/src/atom_vec_tri.cpp b/src/atom_vec_tri.cpp
new file mode 100644
index 0000000000..03aed7aa65
--- /dev/null
+++ b/src/atom_vec_tri.cpp
@@ -0,0 +1,1561 @@
+/* ----------------------------------------------------------------------
+   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 "lmptype.h"
+#include "math.h"
+#include "stdlib.h"
+#include "string.h"
+#include "atom_vec_tri.h"
+#include "math_extra.h"
+#include "atom.h"
+#include "domain.h"
+#include "modify.h"
+#include "force.h"
+#include "fix.h"
+#include "memory.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+
+#define DELTA 10000
+#define DELTA_BONUS 10000
+#define EPSILON 0.001
+
+/* ---------------------------------------------------------------------- */
+
+AtomVecTri::AtomVecTri(LAMMPS *lmp, int narg, char **arg) :
+  AtomVec(lmp, narg, arg)
+{
+  molecular = 0;
+
+  comm_x_only = comm_f_only = 0;
+  size_forward = 7;
+  size_reverse = 6;
+  size_border = 24;
+  size_velocity = 6;
+  size_data_atom = 8;
+  size_data_vel = 7;
+  size_data_bonus = 10;
+  xcol_data = 6;
+
+  atom->tri_flag = 1;
+  atom->molecule_flag = atom->rmass_flag = 1;
+  atom->angmom_flag = atom->torque_flag = 1;
+
+  nlocal_bonus = nghost_bonus = nmax_bonus = 0;
+  bonus = NULL;
+}
+
+/* ---------------------------------------------------------------------- */
+
+AtomVecTri::~AtomVecTri()
+{
+  memory->sfree(bonus);
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecTri::init()
+{
+  AtomVec::init();
+
+  if (domain->dimension != 3)
+    error->all(FLERR,"Atom_style tri can only be used in 3d simulations");
+}
+
+/* ----------------------------------------------------------------------
+   grow atom arrays
+   n = 0 grows arrays by DELTA
+   n > 0 allocates arrays to size n
+------------------------------------------------------------------------- */
+
+void AtomVecTri::grow(int n)
+{
+  if (n == 0) nmax += DELTA;
+  else nmax = n;
+  atom->nmax = nmax;
+
+  tag = memory->grow(atom->tag,nmax,"atom:tag");
+  type = memory->grow(atom->type,nmax,"atom:type");
+  mask = memory->grow(atom->mask,nmax,"atom:mask");
+  image = memory->grow(atom->image,nmax,"atom:image");
+  x = memory->grow(atom->x,nmax,3,"atom:x");
+  v = memory->grow(atom->v,nmax,3,"atom:v");
+  f = memory->grow(atom->f,nmax,3,"atom:f");
+
+  molecule = memory->grow(atom->molecule,nmax,"atom:molecule");
+  rmass = memory->grow(atom->rmass,nmax,"atom:rmass");
+  angmom = memory->grow(atom->angmom,nmax,3,"atom:angmom");
+  torque = memory->grow(atom->torque,nmax,3,"atom:torque");
+  tri = memory->grow(atom->tri,nmax,"atom:tri");
+
+  if (atom->nextra_grow)
+    for (int iextra = 0; iextra < atom->nextra_grow; iextra++)
+      modify->fix[atom->extra_grow[iextra]]->grow_arrays(nmax);
+}
+
+/* ----------------------------------------------------------------------
+   reset local array ptrs
+------------------------------------------------------------------------- */
+
+void AtomVecTri::grow_reset()
+{
+  tag = atom->tag; type = atom->type;
+  mask = atom->mask; image = atom->image;
+  x = atom->x; v = atom->v; f = atom->f;
+  molecule = atom->molecule; rmass = atom->rmass;
+  angmom = atom->angmom; torque = atom->torque;
+}
+
+/* ----------------------------------------------------------------------
+   grow bonus data structure
+------------------------------------------------------------------------- */
+
+void AtomVecTri::grow_bonus()
+{
+  nmax_bonus += DELTA_BONUS;
+  if (nmax_bonus < 0 || nmax_bonus > MAXSMALLINT)
+    error->one(FLERR,"Per-processor system is too big");
+
+  bonus = (Bonus *) memory->srealloc(bonus,nmax_bonus*sizeof(Bonus),
+				     "atom:bonus");
+}
+
+/* ----------------------------------------------------------------------
+   copy atom I info to atom J
+   if delflag and atom J has bonus data, then delete it
+------------------------------------------------------------------------- */
+
+void AtomVecTri::copy(int i, int j, int delflag)
+{
+  tag[j] = tag[i];
+  type[j] = type[i];
+  mask[j] = mask[i];
+  image[j] = image[i];
+  x[j][0] = x[i][0];
+  x[j][1] = x[i][1];
+  x[j][2] = x[i][2];
+  v[j][0] = v[i][0];
+  v[j][1] = v[i][1];
+  v[j][2] = v[i][2];
+
+  molecule[j] = molecule[i];
+  rmass[j] = rmass[i];
+  angmom[j][0] = angmom[i][0];
+  angmom[j][1] = angmom[i][1];
+  angmom[j][2] = angmom[i][2];
+
+  // if delflag and atom J has bonus data, then delete it
+
+  if (delflag && tri[j] >= 0) {
+    copy_bonus(nlocal_bonus-1,tri[j]);
+    nlocal_bonus--;
+  }
+
+  // if atom I has bonus data and not deleting I, repoint I's bonus to J
+
+  if (tri[i] >= 0 && i != j) bonus[tri[i]].ilocal = j;
+  tri[j] = tri[i];
+
+  if (atom->nextra_grow)
+    for (int iextra = 0; iextra < atom->nextra_grow; iextra++)
+      modify->fix[atom->extra_grow[iextra]]->copy_arrays(i,j);
+}
+
+/* ----------------------------------------------------------------------
+   copy bonus data from I to J, effectively deleting the J entry
+   insure index pointers between per-atom and bonus data are updated
+------------------------------------------------------------------------- */
+
+void AtomVecTri::copy_bonus(int i, int j)
+{
+  memcpy(&bonus[j],&bonus[i],sizeof(Bonus));
+  tri[bonus[j].ilocal] = j;
+}
+
+/* ----------------------------------------------------------------------
+   clear ghost info in bonus data
+   called before ghosts are recommunicated in comm and irregular
+------------------------------------------------------------------------- */
+
+void AtomVecTri::clear_bonus()
+{
+  nghost_bonus = 0;
+}
+
+/* ----------------------------------------------------------------------
+   set equilateral tri of size in bonus data for particle I
+   oriented symmetrically in xy plane
+   this may create or delete entry in bonus data
+------------------------------------------------------------------------- */
+
+void AtomVecTri::set_equilateral(int i, double size)
+{
+  if (tri[i] < 0) {
+    if (size == 0.0) return;
+    if (nlocal_bonus == nmax_bonus) grow_bonus();
+    double *quat = bonus[nlocal_bonus].quat;
+    double *c1 = bonus[nlocal_bonus].c1;
+    double *c2 = bonus[nlocal_bonus].c2;
+    double *c3 = bonus[nlocal_bonus].c3;
+    double *inertia = bonus[nlocal_bonus].inertia;
+    quat[0] = 1.0;
+    quat[1] = 0.0;
+    quat[2] = 0.0;
+    quat[3] = 0.0;
+    c1[0] = -size/2.0;
+    c1[1] = -sqrt(3.0)/2.0 * size / 3.0;
+    c1[2] = 0.0;
+    c2[0] = size/2.0;
+    c2[1] = -sqrt(3.0)/2.0 * size / 3.0;
+    c2[2] = 0.0;
+    c3[0] = 0.0;
+    c3[1] = sqrt(3.0)/2.0 * size * 2.0/3.0;
+    c3[2] = 0.0;
+    inertia[0] = sqrt(3.0)/96.0 * size*size*size*size;
+    inertia[1] = sqrt(3.0)/96.0 * size*size*size*size;
+    inertia[2] = sqrt(3.0)/48.0 * size*size*size*size;
+    bonus[nlocal_bonus].ilocal = i;
+    tri[i] = nlocal_bonus++;
+  } else if (size == 0.0) {
+    copy_bonus(nlocal_bonus-1,tri[i]);
+    nlocal_bonus--;
+    tri[i] = -1;
+  } else {
+    double *c1 = bonus[tri[i]].c1;
+    double *c2 = bonus[tri[i]].c2;
+    double *c3 = bonus[tri[i]].c3;
+    double *inertia = bonus[tri[i]].inertia;
+    c1[0] = -size/2.0;
+    c1[1] = -sqrt(3.0)/2.0 * size / 3.0;
+    c1[2] = 0.0;
+    c2[0] = size/2.0;
+    c2[1] = -sqrt(3.0)/2.0 * size / 3.0;
+    c2[2] = 0.0;
+    c3[0] = 0.0;
+    c3[1] = sqrt(3.0)/2.0 * size * 2.0/3.0;
+    c3[2] = 0.0;
+    inertia[0] = sqrt(3.0)/96.0 * size*size*size*size;
+    inertia[1] = sqrt(3.0)/96.0 * size*size*size*size;
+    inertia[2] = sqrt(3.0)/48.0 * size*size*size*size;
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::pack_comm(int n, int *list, double *buf,
+			  int pbc_flag, int *pbc)
+{
+  int i,j,m;
+  double dx,dy,dz;
+  double *quat;
+
+  m = 0;
+  if (pbc_flag == 0) {
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0];
+      buf[m++] = x[j][1];
+      buf[m++] = x[j][2];
+      if (tri[j] >= 0) {
+	quat = bonus[tri[j]].quat;
+	buf[m++] = quat[0];
+	buf[m++] = quat[1];
+	buf[m++] = quat[2];
+	buf[m++] = quat[3];
+      }
+    }
+  } else {
+    if (domain->triclinic == 0) {
+      dx = pbc[0]*domain->xprd;
+      dy = pbc[1]*domain->yprd;
+      dz = pbc[2]*domain->zprd;
+    } else {
+      dx = pbc[0]*domain->xprd + pbc[5]*domain->xy + pbc[4]*domain->xz;
+      dy = pbc[1]*domain->yprd + pbc[3]*domain->yz;
+      dz = pbc[2]*domain->zprd;
+    }
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0] + dx;
+      buf[m++] = x[j][1] + dy;
+      buf[m++] = x[j][2] + dz;
+      if (tri[j] >= 0) {
+	quat = bonus[tri[j]].quat;
+	buf[m++] = quat[0];
+	buf[m++] = quat[1];
+	buf[m++] = quat[2];
+	buf[m++] = quat[3];
+      }
+    }
+  }
+
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::pack_comm_vel(int n, int *list, double *buf,
+			      int pbc_flag, int *pbc)
+{
+  int i,j,m;
+  double dx,dy,dz,dvx,dvy,dvz;
+  double *quat;
+
+  m = 0;
+  if (pbc_flag == 0) {
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0];
+      buf[m++] = x[j][1];
+      buf[m++] = x[j][2];
+      if (tri[j] >= 0) {
+	quat = bonus[tri[j]].quat;
+	buf[m++] = quat[0];
+	buf[m++] = quat[1];
+	buf[m++] = quat[2];
+	buf[m++] = quat[3];
+      }
+      buf[m++] = v[j][0];
+      buf[m++] = v[j][1];
+      buf[m++] = v[j][2];
+      buf[m++] = angmom[j][0];
+      buf[m++] = angmom[j][1];
+      buf[m++] = angmom[j][2];
+    }
+  } else {
+    if (domain->triclinic == 0) {
+      dx = pbc[0]*domain->xprd;
+      dy = pbc[1]*domain->yprd;
+      dz = pbc[2]*domain->zprd;
+    } else {
+      dx = pbc[0]*domain->xprd + pbc[5]*domain->xy + pbc[4]*domain->xz;
+      dy = pbc[1]*domain->yprd + pbc[3]*domain->yz;
+      dz = pbc[2]*domain->zprd;
+    }
+    if (!deform_vremap) {
+      for (i = 0; i < n; i++) {
+	j = list[i];
+	buf[m++] = x[j][0] + dx;
+	buf[m++] = x[j][1] + dy;
+	buf[m++] = x[j][2] + dz;
+	if (tri[j] >= 0) {
+	  quat = bonus[tri[j]].quat;
+	  buf[m++] = quat[0];
+	  buf[m++] = quat[1];
+	  buf[m++] = quat[2];
+	  buf[m++] = quat[3];
+	}
+	buf[m++] = v[j][0];
+	buf[m++] = v[j][1];
+	buf[m++] = v[j][2];
+	buf[m++] = angmom[j][0];
+	buf[m++] = angmom[j][1];
+	buf[m++] = angmom[j][2];
+      }
+    } else {
+      dvx = pbc[0]*h_rate[0] + pbc[5]*h_rate[5] + pbc[4]*h_rate[4];
+      dvy = pbc[1]*h_rate[1] + pbc[3]*h_rate[3];
+      dvz = pbc[2]*h_rate[2];
+      for (i = 0; i < n; i++) {
+	j = list[i];
+	buf[m++] = x[j][0] + dx;
+	buf[m++] = x[j][1] + dy;
+	buf[m++] = x[j][2] + dz;
+	if (tri[j] >= 0) {
+	  quat = bonus[tri[j]].quat;
+	  buf[m++] = quat[0];
+	  buf[m++] = quat[1];
+	  buf[m++] = quat[2];
+	  buf[m++] = quat[3];
+	}
+	if (mask[i] & deform_groupbit) {
+	  buf[m++] = v[j][0] + dvx;
+	  buf[m++] = v[j][1] + dvy;
+	  buf[m++] = v[j][2] + dvz;
+	} else {
+	  buf[m++] = v[j][0];
+	  buf[m++] = v[j][1];
+	  buf[m++] = v[j][2];
+	}
+	buf[m++] = angmom[j][0];
+	buf[m++] = angmom[j][1];
+	buf[m++] = angmom[j][2];
+      }
+    }
+  }
+
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::pack_comm_hybrid(int n, int *list, double *buf)
+{
+  int i,j,m;
+  double *quat;
+
+  m = 0;
+  for (i = 0; i < n; i++) {
+    j = list[i];
+    if (tri[j] >= 0) {
+      quat = bonus[tri[j]].quat;
+      buf[m++] = quat[0];
+      buf[m++] = quat[1];
+      buf[m++] = quat[2];
+      buf[m++] = quat[3];
+    }
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecTri::unpack_comm(int n, int first, double *buf)
+{
+  int i,m,last;
+  double *quat;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    x[i][0] = buf[m++];
+    x[i][1] = buf[m++];
+    x[i][2] = buf[m++];
+    if (tri[i] >= 0) {
+      quat = bonus[tri[i]].quat;
+      quat[0] = buf[m++];
+      quat[1] = buf[m++];
+      quat[2] = buf[m++];
+      quat[3] = buf[m++];
+    }
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecTri::unpack_comm_vel(int n, int first, double *buf)
+{
+  int i,m,last;
+  double *quat;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    x[i][0] = buf[m++];
+    x[i][1] = buf[m++];
+    x[i][2] = buf[m++];
+    if (tri[i] >= 0) {
+      quat = bonus[tri[i]].quat;
+      quat[0] = buf[m++];
+      quat[1] = buf[m++];
+      quat[2] = buf[m++];
+      quat[3] = buf[m++];
+    }
+    v[i][0] = buf[m++];
+    v[i][1] = buf[m++];
+    v[i][2] = buf[m++];
+    angmom[i][0] = buf[m++];
+    angmom[i][1] = buf[m++];
+    angmom[i][2] = buf[m++];
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::unpack_comm_hybrid(int n, int first, double *buf)
+{
+  int i,m,last;
+  double *quat;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++)
+    if (tri[i] >= 0) {
+      quat = bonus[tri[i]].quat;
+      quat[0] = buf[m++];
+      quat[1] = buf[m++];
+      quat[2] = buf[m++];
+      quat[3] = buf[m++];
+    }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::pack_reverse(int n, int first, double *buf)
+{
+  int i,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    buf[m++] = f[i][0];
+    buf[m++] = f[i][1];
+    buf[m++] = f[i][2];
+    buf[m++] = torque[i][0];
+    buf[m++] = torque[i][1];
+    buf[m++] = torque[i][2];
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::pack_reverse_hybrid(int n, int first, double *buf)
+{
+  int i,m,last;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    buf[m++] = torque[i][0];
+    buf[m++] = torque[i][1];
+    buf[m++] = torque[i][2];
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecTri::unpack_reverse(int n, int *list, double *buf)
+{
+  int i,j,m;
+
+  m = 0;
+  for (i = 0; i < n; i++) {
+    j = list[i];
+    f[j][0] += buf[m++];
+    f[j][1] += buf[m++];
+    f[j][2] += buf[m++];
+    torque[j][0] += buf[m++];
+    torque[j][1] += buf[m++];
+    torque[j][2] += buf[m++];
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::unpack_reverse_hybrid(int n, int *list, double *buf)
+{
+  int i,j,m;
+
+  m = 0;
+  for (i = 0; i < n; i++) {
+    j = list[i];
+    torque[j][0] += buf[m++];
+    torque[j][1] += buf[m++];
+    torque[j][2] += buf[m++];
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::pack_border(int n, int *list, double *buf,
+			    int pbc_flag, int *pbc)
+{
+  int i,j,m;
+  double dx,dy,dz;
+  double *quat,*c1,*c2,*c3,*inertia;
+
+  m = 0;
+  if (pbc_flag == 0) {
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0];
+      buf[m++] = x[j][1];
+      buf[m++] = x[j][2];
+      buf[m++] = tag[j];
+      buf[m++] = type[j];
+      buf[m++] = mask[j];
+      buf[m++] = molecule[j];
+      if (tri[j] < 0) buf[m++] = 0;
+      else {
+	buf[m++] = 1;
+	quat = bonus[tri[j]].quat;
+	c1 = bonus[tri[j]].c1;
+	c2 = bonus[tri[j]].c2;
+	c3 = bonus[tri[j]].c3;
+	inertia = bonus[tri[j]].inertia;
+	buf[m++] = quat[0];
+	buf[m++] = quat[1];
+	buf[m++] = quat[2];
+	buf[m++] = quat[3];
+	buf[m++] = c1[0];
+	buf[m++] = c1[1];
+	buf[m++] = c1[2];
+	buf[m++] = c2[0];
+	buf[m++] = c2[1];
+	buf[m++] = c2[2];
+	buf[m++] = c3[0];
+	buf[m++] = c3[1];
+	buf[m++] = c3[2];
+	buf[m++] = inertia[0];
+	buf[m++] = inertia[1];
+	buf[m++] = inertia[2];
+      }
+    }
+  } else {
+    if (domain->triclinic == 0) {
+      dx = pbc[0]*domain->xprd;
+      dy = pbc[1]*domain->yprd;
+      dz = pbc[2]*domain->zprd;
+    } else {
+      dx = pbc[0];
+      dy = pbc[1];
+      dz = pbc[2];
+    }
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0] + dx;
+      buf[m++] = x[j][1] + dy;
+      buf[m++] = x[j][2] + dz;
+      buf[m++] = tag[j];
+      buf[m++] = type[j];
+      buf[m++] = mask[j];
+      buf[m++] = molecule[j];
+      if (tri[j] < 0) buf[m++] = 0;
+      else {
+	buf[m++] = 1;
+	quat = bonus[tri[j]].quat;
+	c1 = bonus[tri[j]].c1;
+	c2 = bonus[tri[j]].c2;
+	c3 = bonus[tri[j]].c3;
+	inertia = bonus[tri[j]].inertia;
+	buf[m++] = quat[0];
+	buf[m++] = quat[1];
+	buf[m++] = quat[2];
+	buf[m++] = quat[3];
+	buf[m++] = c1[0];
+	buf[m++] = c1[1];
+	buf[m++] = c1[2];
+	buf[m++] = c2[0];
+	buf[m++] = c2[1];
+	buf[m++] = c2[2];
+	buf[m++] = c3[0];
+	buf[m++] = c3[1];
+	buf[m++] = c3[2];
+	buf[m++] = inertia[0];
+	buf[m++] = inertia[1];
+	buf[m++] = inertia[2];
+      }
+    }
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::pack_border_vel(int n, int *list, double *buf,
+				int pbc_flag, int *pbc)
+{
+  int i,j,m;
+  double dx,dy,dz,dvx,dvy,dvz;
+  double *quat,*c1,*c2,*c3,*inertia;
+
+  m = 0;
+  if (pbc_flag == 0) {
+    for (i = 0; i < n; i++) {
+      j = list[i];
+      buf[m++] = x[j][0];
+      buf[m++] = x[j][1];
+      buf[m++] = x[j][2];
+      buf[m++] = tag[j];
+      buf[m++] = type[j];
+      buf[m++] = mask[j];
+      buf[m++] = molecule[j];
+      if (tri[j] < 0) buf[m++] = 0;
+      else {
+	buf[m++] = 1;
+	quat = bonus[tri[j]].quat;
+	c1 = bonus[tri[j]].c1;
+	c2 = bonus[tri[j]].c2;
+	c3 = bonus[tri[j]].c3;
+	inertia = bonus[tri[j]].inertia;
+	buf[m++] = quat[0];
+	buf[m++] = quat[1];
+	buf[m++] = quat[2];
+	buf[m++] = quat[3];
+	buf[m++] = c1[0];
+	buf[m++] = c1[1];
+	buf[m++] = c1[2];
+	buf[m++] = c2[0];
+	buf[m++] = c2[1];
+	buf[m++] = c2[2];
+	buf[m++] = c3[0];
+	buf[m++] = c3[1];
+	buf[m++] = c3[2];
+	buf[m++] = inertia[0];
+	buf[m++] = inertia[1];
+	buf[m++] = inertia[2];
+      }
+      buf[m++] = v[j][0];
+      buf[m++] = v[j][1];
+      buf[m++] = v[j][2];
+      buf[m++] = angmom[j][0];
+      buf[m++] = angmom[j][1];
+      buf[m++] = angmom[j][2];
+    }
+  } else {
+    if (domain->triclinic == 0) {
+      dx = pbc[0]*domain->xprd;
+      dy = pbc[1]*domain->yprd;
+      dz = pbc[2]*domain->zprd;
+    } else {
+      dx = pbc[0];
+      dy = pbc[1];
+      dz = pbc[2];
+    }
+    if (!deform_vremap) {
+      for (i = 0; i < n; i++) {
+	j = list[i];
+	buf[m++] = x[j][0] + dx;
+	buf[m++] = x[j][1] + dy;
+	buf[m++] = x[j][2] + dz;
+	buf[m++] = tag[j];
+	buf[m++] = type[j];
+	buf[m++] = mask[j];
+	buf[m++] = molecule[j];
+	if (tri[j] < 0) buf[m++] = 0;
+	else {
+	  buf[m++] = 1;
+	  quat = bonus[tri[j]].quat;
+	  c1 = bonus[tri[j]].c1;
+	  c2 = bonus[tri[j]].c2;
+	  c3 = bonus[tri[j]].c3;
+	  inertia = bonus[tri[j]].inertia;
+	  buf[m++] = quat[0];
+	  buf[m++] = quat[1];
+	  buf[m++] = quat[2];
+	  buf[m++] = quat[3];
+	  buf[m++] = c1[0];
+	  buf[m++] = c1[1];
+	  buf[m++] = c1[2];
+	  buf[m++] = c2[0];
+	  buf[m++] = c2[1];
+	  buf[m++] = c2[2];
+	  buf[m++] = c3[0];
+	  buf[m++] = c3[1];
+	  buf[m++] = c3[2];
+	  buf[m++] = inertia[0];
+	  buf[m++] = inertia[1];
+	  buf[m++] = inertia[2];
+	}
+	buf[m++] = v[j][0];
+	buf[m++] = v[j][1];
+	buf[m++] = v[j][2];
+	buf[m++] = angmom[j][0];
+	buf[m++] = angmom[j][1];
+	buf[m++] = angmom[j][2];
+      }
+    } else {
+      dvx = pbc[0]*h_rate[0] + pbc[5]*h_rate[5] + pbc[4]*h_rate[4];
+      dvy = pbc[1]*h_rate[1] + pbc[3]*h_rate[3];
+      dvz = pbc[2]*h_rate[2];
+      for (i = 0; i < n; i++) {
+	j = list[i];
+	buf[m++] = x[j][0] + dx;
+	buf[m++] = x[j][1] + dy;
+	buf[m++] = x[j][2] + dz;
+	buf[m++] = tag[j];
+	buf[m++] = type[j];
+	buf[m++] = mask[j];
+	buf[m++] = molecule[j];
+	if (tri[j] < 0) buf[m++] = 0;
+	else {
+	  buf[m++] = 1;
+	  quat = bonus[tri[j]].quat;
+	  c1 = bonus[tri[j]].c1;
+	  c2 = bonus[tri[j]].c2;
+	  c3 = bonus[tri[j]].c3;
+	  inertia = bonus[tri[j]].inertia;
+	  buf[m++] = quat[0];
+	  buf[m++] = quat[1];
+	  buf[m++] = quat[2];
+	  buf[m++] = quat[3];
+	  buf[m++] = c1[0];
+	  buf[m++] = c1[1];
+	  buf[m++] = c1[2];
+	  buf[m++] = c2[0];
+	  buf[m++] = c2[1];
+	  buf[m++] = c2[2];
+	  buf[m++] = c3[0];
+	  buf[m++] = c3[1];
+	  buf[m++] = c3[2];
+	  buf[m++] = inertia[0];
+	  buf[m++] = inertia[1];
+	  buf[m++] = inertia[2];
+	}
+	if (mask[i] & deform_groupbit) {
+	  buf[m++] = v[j][0] + dvx;
+	  buf[m++] = v[j][1] + dvy;
+	  buf[m++] = v[j][2] + dvz;
+	} else {
+	  buf[m++] = v[j][0];
+	  buf[m++] = v[j][1];
+	  buf[m++] = v[j][2];
+	}
+	buf[m++] = angmom[j][0];
+	buf[m++] = angmom[j][1];
+	buf[m++] = angmom[j][2];
+      }
+    }
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::pack_border_hybrid(int n, int *list, double *buf)
+{
+  int i,j,m;
+  double *quat,*c1,*c2,*c3,*inertia;
+
+  m = 0;
+  for (i = 0; i < n; i++) {
+    j = list[i];
+    buf[m++] = molecule[j];
+    if (tri[j] < 0) buf[m++] = 0;
+    else {
+      buf[m++] = 1;
+      quat = bonus[tri[j]].quat;
+      c1 = bonus[tri[j]].c1;
+      c2 = bonus[tri[j]].c2;
+      c3 = bonus[tri[j]].c3;
+      inertia = bonus[tri[j]].inertia;
+      buf[m++] = quat[0];
+      buf[m++] = quat[1];
+      buf[m++] = quat[2];
+      buf[m++] = quat[3];
+      buf[m++] = c1[0];
+      buf[m++] = c1[1];
+      buf[m++] = c1[2];
+      buf[m++] = c2[0];
+      buf[m++] = c2[1];
+      buf[m++] = c2[2];
+      buf[m++] = c3[0];
+      buf[m++] = c3[1];
+      buf[m++] = c3[2];
+      buf[m++] = inertia[0];
+      buf[m++] = inertia[1];
+      buf[m++] = inertia[2];
+    }
+  }
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecTri::unpack_border(int n, int first, double *buf)
+{
+  int i,j,m,last;
+  double *quat,*c1,*c2,*c3,*inertia;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    if (i == nmax) grow(0);
+    x[i][0] = buf[m++];
+    x[i][1] = buf[m++];
+    x[i][2] = buf[m++];
+    tag[i] = static_cast<int> (buf[m++]);
+    type[i] = static_cast<int> (buf[m++]);
+    mask[i] = static_cast<int> (buf[m++]);
+    molecule[i] = static_cast<int> (buf[m++]);
+    tri[i] = static_cast<int> (buf[m++]);
+    if (tri[i] == 0) tri[i] = -1;
+    else {
+      j = nlocal_bonus + nghost_bonus;
+      if (j == nmax_bonus) grow_bonus();
+      quat = bonus[j].quat;
+      c1 = bonus[j].c1;
+      c2 = bonus[j].c2;
+      c3 = bonus[j].c3;
+      inertia = bonus[j].inertia;
+      quat[0] = buf[m++];
+      quat[1] = buf[m++];
+      quat[2] = buf[m++];
+      quat[3] = buf[m++];
+      c1[0] = buf[m++];
+      c1[1] = buf[m++];
+      c1[2] = buf[m++];
+      c2[0] = buf[m++];
+      c2[1] = buf[m++];
+      c2[2] = buf[m++];
+      c3[0] = buf[m++];
+      c3[1] = buf[m++];
+      c3[2] = buf[m++];
+      inertia[0] = buf[m++];
+      inertia[1] = buf[m++];
+      inertia[2] = buf[m++];
+      bonus[j].ilocal = i;
+      tri[i] = j;
+      nghost_bonus++;
+    }
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void AtomVecTri::unpack_border_vel(int n, int first, double *buf)
+{
+  int i,j,m,last;
+  double *quat,*c1,*c2,*c3,*inertia;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    if (i == nmax) grow(0);
+    x[i][0] = buf[m++];
+    x[i][1] = buf[m++];
+    x[i][2] = buf[m++];
+    tag[i] = static_cast<int> (buf[m++]);
+    type[i] = static_cast<int> (buf[m++]);
+    mask[i] = static_cast<int> (buf[m++]);
+    molecule[i] = static_cast<int> (buf[m++]);
+    tri[i] = static_cast<int> (buf[m++]);
+    if (tri[i] == 0) tri[i] = -1;
+    else {
+      j = nlocal_bonus + nghost_bonus;
+      if (j == nmax_bonus) grow_bonus();
+      quat = bonus[j].quat;
+      c1 = bonus[j].c1;
+      c2 = bonus[j].c2;
+      c3 = bonus[j].c3;
+      inertia = bonus[j].inertia;
+      quat[0] = buf[m++];
+      quat[1] = buf[m++];
+      quat[2] = buf[m++];
+      quat[3] = buf[m++];
+      c1[0] = buf[m++];
+      c1[1] = buf[m++];
+      c1[2] = buf[m++];
+      c2[0] = buf[m++];
+      c2[1] = buf[m++];
+      c2[2] = buf[m++];
+      c3[0] = buf[m++];
+      c3[1] = buf[m++];
+      c3[2] = buf[m++];
+      inertia[0] = buf[m++];
+      inertia[1] = buf[m++];
+      inertia[2] = buf[m++];
+      bonus[j].ilocal = i;
+      tri[i] = j;
+      nghost_bonus++;
+    }
+    v[i][0] = buf[m++];
+    v[i][1] = buf[m++];
+    v[i][2] = buf[m++];
+    angmom[i][0] = buf[m++];
+    angmom[i][1] = buf[m++];
+    angmom[i][2] = buf[m++];
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::unpack_border_hybrid(int n, int first, double *buf)
+{
+  int i,j,m,last;
+  double *quat,*c1,*c2,*c3,*inertia;
+
+  m = 0;
+  last = first + n;
+  for (i = first; i < last; i++) {
+    molecule[i] = static_cast<int> (buf[m++]);
+    tri[i] = static_cast<int> (buf[m++]);
+    if (tri[i] == 0) tri[i] = -1;
+    else {
+      j = nlocal_bonus + nghost_bonus;
+      if (j == nmax_bonus) grow_bonus();
+      quat = bonus[j].quat;
+      c1 = bonus[j].c1;
+      c2 = bonus[j].c2;
+      c3 = bonus[j].c3;
+      inertia = bonus[j].inertia;
+      quat[0] = buf[m++];
+      quat[1] = buf[m++];
+      quat[2] = buf[m++];
+      quat[3] = buf[m++];
+      c1[0] = buf[m++];
+      c1[1] = buf[m++];
+      c1[2] = buf[m++];
+      c2[0] = buf[m++];
+      c2[1] = buf[m++];
+      c2[2] = buf[m++];
+      c3[0] = buf[m++];
+      c3[1] = buf[m++];
+      c3[2] = buf[m++];
+      inertia[0] = buf[m++];
+      inertia[1] = buf[m++];
+      inertia[2] = buf[m++];
+      bonus[j].ilocal = i;
+      tri[i] = j;
+      nghost_bonus++;
+    }
+  }
+  return m;
+}
+
+/* ----------------------------------------------------------------------
+   pack data for atom I for sending to another proc
+   xyz must be 1st 3 values, so comm::exchange() can test on them 
+------------------------------------------------------------------------- */
+
+int AtomVecTri::pack_exchange(int i, double *buf)
+{
+  int m = 1;
+  buf[m++] = x[i][0];
+  buf[m++] = x[i][1];
+  buf[m++] = x[i][2];
+  buf[m++] = v[i][0];
+  buf[m++] = v[i][1];
+  buf[m++] = v[i][2];
+  buf[m++] = tag[i];
+  buf[m++] = type[i];
+  buf[m++] = mask[i];
+  buf[m++] = image[i];
+
+  buf[m++] = molecule[i];
+  buf[m++] = rmass[i];
+  buf[m++] = angmom[i][0];
+  buf[m++] = angmom[i][1];
+  buf[m++] = angmom[i][2];
+
+  if (tri[i] < 0) buf[m++] = 0;
+  else {
+    buf[m++] = 1;
+    int j = tri[i];
+    double *quat = bonus[j].quat;
+    double *c1 = bonus[j].c1;
+    double *c2 = bonus[j].c2;
+    double *c3 = bonus[j].c3;
+    double *inertia = bonus[j].inertia;
+    buf[m++] = quat[0];
+    buf[m++] = quat[1];
+    buf[m++] = quat[2];
+    buf[m++] = quat[3];
+    buf[m++] = c1[0];
+    buf[m++] = c1[1];
+    buf[m++] = c1[2];
+    buf[m++] = c2[0];
+    buf[m++] = c2[1];
+    buf[m++] = c2[2];
+    buf[m++] = c3[0];
+    buf[m++] = c3[1];
+    buf[m++] = c3[2];
+    buf[m++] = inertia[0];
+    buf[m++] = inertia[1];
+    buf[m++] = inertia[2];
+  }
+
+  if (atom->nextra_grow)
+    for (int iextra = 0; iextra < atom->nextra_grow; iextra++) 
+      m += modify->fix[atom->extra_grow[iextra]]->pack_exchange(i,&buf[m]);
+
+  buf[0] = m;
+  return m;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int AtomVecTri::unpack_exchange(double *buf)
+{
+  int nlocal = atom->nlocal;
+  if (nlocal == nmax) grow(0);
+
+  int m = 1;
+  x[nlocal][0] = buf[m++];
+  x[nlocal][1] = buf[m++];
+  x[nlocal][2] = buf[m++];
+  v[nlocal][0] = buf[m++];
+  v[nlocal][1] = buf[m++];
+  v[nlocal][2] = buf[m++];
+  tag[nlocal] = static_cast<int> (buf[m++]);
+  type[nlocal] = static_cast<int> (buf[m++]);
+  mask[nlocal] = static_cast<int> (buf[m++]);
+  image[nlocal] = static_cast<int> (buf[m++]);
+
+  molecule[nlocal] = static_cast<int> (buf[m++]);
+  rmass[nlocal] = buf[m++];
+  angmom[nlocal][0] = buf[m++];
+  angmom[nlocal][1] = buf[m++];
+  angmom[nlocal][2] = buf[m++];
+
+  tri[nlocal] = static_cast<int> (buf[m++]);
+  if (tri[nlocal] == 0) tri[nlocal] = -1;
+  else {
+    if (nlocal_bonus == nmax_bonus) grow_bonus();
+    double *quat = bonus[nlocal_bonus].quat;
+    double *c1 = bonus[nlocal_bonus].c1;
+    double *c2 = bonus[nlocal_bonus].c2;
+    double *c3 = bonus[nlocal_bonus].c3;
+    double *inertia = bonus[nlocal_bonus].inertia;
+    quat[0] = buf[m++];
+    quat[1] = buf[m++];
+    quat[2] = buf[m++];
+    quat[3] = buf[m++];
+    c1[0] = buf[m++];
+    c1[1] = buf[m++];
+    c1[2] = buf[m++];
+    c2[0] = buf[m++];
+    c2[1] = buf[m++];
+    c2[2] = buf[m++];
+    c3[0] = buf[m++];
+    c3[1] = buf[m++];
+    c3[2] = buf[m++];
+    inertia[0] = buf[m++];
+    inertia[1] = buf[m++];
+    inertia[2] = buf[m++];
+    bonus[nlocal_bonus].ilocal = nlocal;
+    tri[nlocal] = nlocal_bonus++;
+  }
+
+  if (atom->nextra_grow)
+    for (int iextra = 0; iextra < atom->nextra_grow; iextra++) 
+      m += modify->fix[atom->extra_grow[iextra]]->
+	unpack_exchange(nlocal,&buf[m]);
+
+  atom->nlocal++;
+  return m;
+}
+
+/* ----------------------------------------------------------------------
+   size of restart data for all atoms owned by this proc
+   include extra data stored by fixes
+------------------------------------------------------------------------- */
+
+int AtomVecTri::size_restart()
+{
+  int i;
+
+  int n = 0;
+  int nlocal = atom->nlocal;
+  for (i = 0; i < nlocal; i++)
+    if (tri[i] >= 0) n += 33;
+    else n += 17;
+
+  if (atom->nextra_restart)
+    for (int iextra = 0; iextra < atom->nextra_restart; iextra++) 
+      for (i = 0; i < nlocal; i++)
+	n += modify->fix[atom->extra_restart[iextra]]->size_restart(i);
+
+  return n;
+}
+
+/* ----------------------------------------------------------------------
+   pack atom I's data for restart file including extra quantities
+   xyz must be 1st 3 values, so that read_restart can test on them
+   molecular types may be negative, but write as positive   
+------------------------------------------------------------------------- */
+
+int AtomVecTri::pack_restart(int i, double *buf)
+{
+  int m = 1;
+  buf[m++] = x[i][0];
+  buf[m++] = x[i][1];
+  buf[m++] = x[i][2];
+  buf[m++] = tag[i];
+  buf[m++] = type[i];
+  buf[m++] = mask[i];
+  buf[m++] = image[i];
+  buf[m++] = v[i][0];
+  buf[m++] = v[i][1];
+  buf[m++] = v[i][2];
+
+  buf[m++] = molecule[i];
+  buf[m++] = rmass[i];
+  buf[m++] = angmom[i][0];
+  buf[m++] = angmom[i][1];
+  buf[m++] = angmom[i][2];
+
+  if (tri[i] < 0) buf[m++] = 0;
+  else {
+    buf[m++] = 1;
+    int j = tri[i];
+    double *quat = bonus[j].quat;
+    double *c1 = bonus[j].c1;
+    double *c2 = bonus[j].c2;
+    double *c3 = bonus[j].c3;
+    double *inertia = bonus[j].inertia;
+    buf[m++] = quat[0];
+    buf[m++] = quat[1];
+    buf[m++] = quat[2];
+    buf[m++] = quat[3];
+    buf[m++] = c1[0];
+    buf[m++] = c1[1];
+    buf[m++] = c1[2];
+    buf[m++] = c2[0];
+    buf[m++] = c2[1];
+    buf[m++] = c2[2];
+    buf[m++] = c3[0];
+    buf[m++] = c3[1];
+    buf[m++] = c3[2];
+    buf[m++] = inertia[0];
+    buf[m++] = inertia[1];
+    buf[m++] = inertia[2];
+  }
+
+  if (atom->nextra_restart)
+    for (int iextra = 0; iextra < atom->nextra_restart; iextra++) 
+      m += modify->fix[atom->extra_restart[iextra]]->pack_restart(i,&buf[m]);
+
+  buf[0] = m;
+  return m;
+}
+
+/* ----------------------------------------------------------------------
+   unpack data for one atom from restart file including extra quantities
+------------------------------------------------------------------------- */
+
+int AtomVecTri::unpack_restart(double *buf)
+{
+  int nlocal = atom->nlocal;
+  if (nlocal == nmax) {
+    grow(0);
+    if (atom->nextra_store)
+      memory->grow(atom->extra,nmax,atom->nextra_store,"atom:extra");
+  }
+
+  int m = 1;
+  x[nlocal][0] = buf[m++];
+  x[nlocal][1] = buf[m++];
+  x[nlocal][2] = buf[m++];
+  tag[nlocal] = static_cast<int> (buf[m++]);
+  type[nlocal] = static_cast<int> (buf[m++]);
+  mask[nlocal] = static_cast<int> (buf[m++]);
+  image[nlocal] = static_cast<int> (buf[m++]);
+  v[nlocal][0] = buf[m++];
+  v[nlocal][1] = buf[m++];
+  v[nlocal][2] = buf[m++];
+
+  molecule[nlocal] = static_cast<int> (buf[m++]);
+  rmass[nlocal] = buf[m++];
+  angmom[nlocal][0] = buf[m++];
+  angmom[nlocal][1] = buf[m++];
+  angmom[nlocal][2] = buf[m++];
+
+  tri[nlocal] = static_cast<int> (buf[m++]);
+  if (tri[nlocal] == 0) tri[nlocal] = -1;
+  else {
+    if (nlocal_bonus == nmax_bonus) grow_bonus();
+    double *quat = bonus[nlocal_bonus].quat;
+    double *c1 = bonus[nlocal_bonus].c1;
+    double *c2 = bonus[nlocal_bonus].c2;
+    double *c3 = bonus[nlocal_bonus].c3;
+    double *inertia = bonus[nlocal_bonus].inertia;
+    quat[0] = buf[m++];
+    quat[1] = buf[m++];
+    quat[2] = buf[m++];
+    quat[3] = buf[m++];
+    c1[0] = buf[m++];
+    c1[1] = buf[m++];
+    c1[2] = buf[m++];
+    c2[0] = buf[m++];
+    c2[1] = buf[m++];
+    c2[2] = buf[m++];
+    c3[0] = buf[m++];
+    c3[1] = buf[m++];
+    c3[2] = buf[m++];
+    inertia[0] = buf[m++];
+    inertia[1] = buf[m++];
+    inertia[2] = buf[m++];
+    bonus[nlocal_bonus].ilocal = nlocal;
+    tri[nlocal] = nlocal_bonus++;
+  }
+
+  double **extra = atom->extra;
+  if (atom->nextra_store) {
+    int size = static_cast<int> (buf[0]) - m;
+    for (int i = 0; i < size; i++) extra[nlocal][i] = buf[m++];
+  }
+
+  atom->nlocal++;
+  return m;
+}
+
+/* ----------------------------------------------------------------------
+   create one atom of itype at coord
+   set other values to defaults
+------------------------------------------------------------------------- */
+
+void AtomVecTri::create_atom(int itype, double *coord)
+{
+  int nlocal = atom->nlocal;
+  if (nlocal == nmax) grow(0);
+
+  tag[nlocal] = 0;
+  type[nlocal] = itype;
+  x[nlocal][0] = coord[0];
+  x[nlocal][1] = coord[1];
+  x[nlocal][2] = coord[2];
+  mask[nlocal] = 1;
+  image[nlocal] = (512 << 20) | (512 << 10) | 512;
+  v[nlocal][0] = 0.0;
+  v[nlocal][1] = 0.0;
+  v[nlocal][2] = 0.0;
+
+  molecule[nlocal] = 0;
+  rmass[nlocal] = 1.0;
+  angmom[nlocal][0] = 0.0;
+  angmom[nlocal][1] = 0.0;
+  angmom[nlocal][2] = 0.0;
+  tri[nlocal] = -1;
+
+  atom->nlocal++;
+}
+
+/* ----------------------------------------------------------------------
+   unpack one tri from Atoms section of data file
+   initialize other atom quantities
+------------------------------------------------------------------------- */
+
+void AtomVecTri::data_atom(double *coord, int imagetmp, char **values)
+{
+  int nlocal = atom->nlocal;
+  if (nlocal == nmax) grow(0);
+
+  tag[nlocal] = atoi(values[0]);
+  if (tag[nlocal] <= 0)
+    error->one(FLERR,"Invalid atom ID in Atoms section of data file");
+
+  molecule[nlocal] = atoi(values[1]);
+
+  type[nlocal] = atoi(values[2]);
+  if (type[nlocal] <= 0 || type[nlocal] > atom->ntypes)
+    error->one(FLERR,"Invalid atom type in Atoms section of data file");
+
+  tri[nlocal] = atoi(values[3]);
+  if (tri[nlocal] == 0) tri[nlocal] = -1;
+  else if (tri[nlocal] == 1) tri[nlocal] = 0;
+  else error->one(FLERR,"Invalid atom type in Atoms section of data file");
+
+  rmass[nlocal] = atof(values[4]);
+  if (rmass[nlocal] <= 0.0)
+    error->one(FLERR,"Invalid density in Atoms section of data file");
+
+  x[nlocal][0] = coord[0];
+  x[nlocal][1] = coord[1];
+  x[nlocal][2] = coord[2];
+
+  image[nlocal] = imagetmp;
+
+  mask[nlocal] = 1;
+  v[nlocal][0] = 0.0;
+  v[nlocal][1] = 0.0;
+  v[nlocal][2] = 0.0;
+  angmom[nlocal][0] = 0.0;
+  angmom[nlocal][1] = 0.0;
+  angmom[nlocal][2] = 0.0;
+
+  atom->nlocal++;
+}
+
+/* ----------------------------------------------------------------------
+   unpack hybrid quantities from one tri in Atoms section of data file
+   initialize other atom quantities for this sub-style
+------------------------------------------------------------------------- */
+
+int AtomVecTri::data_atom_hybrid(int nlocal, char **values)
+{
+  molecule[nlocal] = atoi(values[0]);
+
+  tri[nlocal] = atoi(values[1]);
+  if (tri[nlocal] == 0) tri[nlocal] = -1;
+  else if (tri[nlocal] == 1) tri[nlocal] = 0;
+  else error->one(FLERR,"Invalid atom type in Atoms section of data file");
+
+  rmass[nlocal] = atof(values[2]);
+  if (rmass[nlocal] <= 0.0)
+    error->one(FLERR,"Invalid density in Atoms section of data file");
+
+  return 3;
+}
+
+/* ----------------------------------------------------------------------
+   unpack one tri from Tris section of data file
+------------------------------------------------------------------------- */
+
+void AtomVecTri::data_atom_bonus(int m, char **values)
+{
+  if (tri[m]) error->one(FLERR,"Assigning tri parameters to non-tri atom");
+
+  if (nlocal_bonus == nmax_bonus) grow_bonus();
+
+  double c1[3],c2[3],c3[3];
+  c1[0] = atof(values[0]);
+  c1[1] = atof(values[1]);
+  c1[2] = atof(values[2]);
+  c2[0] = atof(values[3]);
+  c2[1] = atof(values[4]);
+  c2[2] = atof(values[5]);
+  c3[0] = atof(values[6]);
+  c3[1] = atof(values[7]);
+  c3[2] = atof(values[8]);
+
+  // check for duplicate points
+
+  if (c1[0] == c2[0] && c1[1] == c2[1] && c1[2] == c2[2])
+    error->one(FLERR,"Invalid shape in Triangles section of data file");
+  if (c1[0] == c3[0] && c1[1] == c3[1] && c1[2] == c3[2])
+    error->one(FLERR,"Invalid shape in Triangles section of data file");
+  if (c2[0] == c3[0] && c2[1] == c3[1] && c2[2] == c3[2])
+    error->one(FLERR,"Invalid shape in Triangles section of data file");
+
+  // size = length of one edge
+
+  double c2mc1[2],c3mc1[3];
+  MathExtra::sub3(c2,c1,c2mc1);
+  MathExtra::sub3(c3,c1,c3mc1);
+  double size = MAX(MathExtra::len3(c2mc1),MathExtra::len3(c3mc1));
+
+  // centroid = 1/3 of sum of vertices
+
+  double centroid[3];
+  centroid[0] = (c1[0]+c2[0]+c3[0]) / 3.0;
+  centroid[1] = (c1[1]+c2[1]+c3[1]) / 3.0;
+  centroid[2] = (c1[2]+c2[2]+c3[2]) / 3.0;
+
+  double dx = centroid[0] - x[m][0];
+  double dy = centroid[1] - x[m][1];
+  double dz = centroid[2] - x[m][2];
+  double delta = sqrt(dx*dx + dy*dy + dz*dz);
+
+  if (delta/size > EPSILON)
+    error->one(FLERR,"Inconsistent triangle in data file");
+
+  x[m][0] = centroid[0];
+  x[m][1] = centroid[1];
+  x[m][2] = centroid[2];
+
+  // reset tri mass
+  // previously stored density in rmass
+  // tri area = 0.5 len(U x V), where U,V are edge vectors from one vertex
+
+  double norm[3];
+  MathExtra::cross3(c2mc1,c3mc1,norm);
+  double area = 0.5 * MathExtra::len3(norm);
+  rmass[m] *= area;
+
+  // inertia = inertia tensor of triangle as 6-vector in Voigt notation
+
+  double inertia[6];
+  MathExtra::inertia_triangle(c1,c2,c3,rmass[m],inertia);
+
+  // diagonalize inertia tensor via Jacobi rotations
+  // bonus[].inertia = 3 eigenvalues = principal moments of inertia
+  // evectors and exzy_space = 3 evectors = principal axes of triangle
+
+  double tensor[3][3],evectors[3][3];
+  tensor[0][0] = inertia[0];
+  tensor[1][1] = inertia[1];
+  tensor[2][2] = inertia[2];
+  tensor[1][2] = tensor[2][1] = inertia[3];
+  tensor[0][2] = tensor[2][0] = inertia[4];
+  tensor[0][1] = tensor[1][0] = inertia[5];
+
+  int ierror = MathExtra::jacobi(tensor,bonus[nlocal_bonus].inertia,evectors);
+  if (ierror) error->one(FLERR,"Insufficient Jacobi rotations for triangle");
+  
+  double ex_space[3],ey_space[3],ez_space[3];
+  ex_space[0] = evectors[0][0];
+  ex_space[1] = evectors[1][0];
+  ex_space[2] = evectors[2][0];
+  ey_space[0] = evectors[0][1];
+  ey_space[1] = evectors[1][1];
+  ey_space[2] = evectors[2][1];
+  ez_space[0] = evectors[0][2];
+  ez_space[1] = evectors[1][2];
+  ez_space[2] = evectors[2][2];
+
+  // enforce 3 orthogonal vectors as a right-handed coordinate system
+  // flip 3rd vector if needed
+
+  MathExtra::cross3(ex_space,ey_space,norm);
+  if (MathExtra::dot3(norm,ez_space) < 0.0) MathExtra::negate3(ez_space);
+
+  // create initial quaternion
+  
+  MathExtra::exyz_to_q(ex_space,ey_space,ez_space,bonus[nlocal_bonus].quat);
+
+  // bonus c1,c2,c3 = displacement of c1,c2,c3 from centroid
+  // in basis of principal axes
+
+  double disp[3];
+  MathExtra::sub3(c1,centroid,disp);
+  MathExtra::transpose_matvec(ex_space,ey_space,ez_space,
+			      disp,bonus[nlocal_bonus].c1);
+  MathExtra::sub3(c2,centroid,disp);
+  MathExtra::transpose_matvec(ex_space,ey_space,ez_space,
+			      disp,bonus[nlocal_bonus].c2);
+  MathExtra::sub3(c3,centroid,disp);
+  MathExtra::transpose_matvec(ex_space,ey_space,ez_space,
+			      disp,bonus[nlocal_bonus].c3);
+
+  bonus[nlocal_bonus].ilocal = m;
+  tri[m] = nlocal_bonus++;
+}
+
+/* ----------------------------------------------------------------------
+   unpack one tri from Velocities section of data file
+------------------------------------------------------------------------- */
+
+void AtomVecTri::data_vel(int m, char **values)
+{
+  v[m][0] = atof(values[0]);
+  v[m][1] = atof(values[1]);
+  v[m][2] = atof(values[2]);
+  angmom[m][0] = atof(values[3]);
+  angmom[m][1] = atof(values[4]);
+  angmom[m][2] = atof(values[5]);
+}
+
+/* ----------------------------------------------------------------------
+   unpack hybrid quantities from one tri in Velocities section of data file
+------------------------------------------------------------------------- */
+
+int AtomVecTri::data_vel_hybrid(int m, char **values)
+{
+  angmom[m][0] = atof(values[0]);
+  angmom[m][1] = atof(values[1]);
+  angmom[m][2] = atof(values[2]);
+  return 3;
+}
+
+/* ----------------------------------------------------------------------
+   return # of bytes of allocated memory 
+------------------------------------------------------------------------- */
+
+bigint AtomVecTri::memory_usage()
+{
+  bigint bytes = 0;
+
+  if (atom->memcheck("tag")) bytes += memory->usage(tag,nmax);
+  if (atom->memcheck("type")) bytes += memory->usage(type,nmax);
+  if (atom->memcheck("mask")) bytes += memory->usage(mask,nmax);
+  if (atom->memcheck("image")) bytes += memory->usage(image,nmax);
+  if (atom->memcheck("x")) bytes += memory->usage(x,nmax,3);
+  if (atom->memcheck("v")) bytes += memory->usage(v,nmax,3);
+  if (atom->memcheck("f")) bytes += memory->usage(f,nmax,3);
+
+  if (atom->memcheck("molecule")) bytes += memory->usage(molecule,nmax);
+  if (atom->memcheck("rmass")) bytes += memory->usage(rmass,nmax);
+  if (atom->memcheck("angmom")) bytes += memory->usage(angmom,nmax,3);
+  if (atom->memcheck("torque")) bytes += memory->usage(torque,nmax,3);
+  if (atom->memcheck("tri")) bytes += memory->usage(tri,nmax);
+
+  bytes += nmax_bonus*sizeof(Bonus);
+
+  return bytes;
+}
diff --git a/src/atom_vec_tri.h b/src/atom_vec_tri.h
new file mode 100644
index 0000000000..33f3e9cd6e
--- /dev/null
+++ b/src/atom_vec_tri.h
@@ -0,0 +1,97 @@
+/* ----------------------------------------------------------------------
+   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 ATOM_CLASS
+
+AtomStyle(tri,AtomVecTri)
+
+#else
+
+#ifndef LMP_ATOM_VEC_TRI_H
+#define LMP_ATOM_VEC_TRI_H
+
+#include "atom_vec.h"
+
+namespace LAMMPS_NS {
+
+class AtomVecTri : public AtomVec {
+ public:
+  struct Bonus {
+    double quat[4];
+    double c1[3],c2[3],c3[3];
+    double inertia[3];
+    int ilocal;
+  };
+  struct Bonus *bonus;
+
+  AtomVecTri(class LAMMPS *, int, char **);
+  ~AtomVecTri();
+  void init();
+  void grow(int);
+  void grow_reset();
+  void copy(int, int, int);
+  int pack_comm(int, int *, double *, int, int *);
+  int pack_comm_vel(int, int *, double *, int, int *);
+  int pack_comm_hybrid(int, int *, double *);
+  void unpack_comm(int, int, double *);
+  void unpack_comm_vel(int, int, double *);
+  int unpack_comm_hybrid(int, int, double *);
+  int pack_reverse(int, int, double *);
+  int pack_reverse_hybrid(int, int, double *);
+  void unpack_reverse(int, int *, double *);
+  int unpack_reverse_hybrid(int, int *, double *);
+  int pack_border(int, int *, double *, int, int *);
+  int pack_border_vel(int, int *, double *, int, int *);
+  int pack_border_hybrid(int, int *, double *);
+  void unpack_border(int, int, double *);
+  void unpack_border_vel(int, int, double *);
+  int unpack_border_hybrid(int, int, double *);
+  int pack_exchange(int, double *);
+  int unpack_exchange(double *);
+  int size_restart();
+  int pack_restart(int, double *);
+  int unpack_restart(double *);
+  void create_atom(int, double *);
+  void data_atom(double *, int, char **);
+  int data_atom_hybrid(int, char **);
+  void data_vel(int, char **);
+  int data_vel_hybrid(int, char **);
+  bigint memory_usage();
+
+  // manipulate Bonus data structure for extra atom info
+
+  void clear_bonus();
+  void data_atom_bonus(int, char **);
+
+  // unique to AtomVecTri
+
+  void set_equilateral(int, double);
+
+ private:
+  int *tag,*type,*mask,*image;
+  double **x,**v,**f;
+  int *molecule;
+  double *rmass;
+  double **angmom,**torque;
+  int *tri;
+
+  int nlocal_bonus,nghost_bonus,nmax_bonus;
+
+  void grow_bonus();
+  void copy_bonus(int, int);
+};
+
+}
+
+#endif
+#endif