diff --git a/src/MANYBODY/pair_nb3b_harmonic.cpp b/src/MANYBODY/pair_nb3b_harmonic.cpp
new file mode 100644
index 0000000000..1130479d3f
--- /dev/null
+++ b/src/MANYBODY/pair_nb3b_harmonic.cpp
@@ -0,0 +1,532 @@
+/* ----------------------------------------------------------------------
+   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.
+------------------------------------------------------------------------- */
+
+/* ----------------------------------------------------------------------
+   Contributing author: Todd R. Zeitler (SNL)
+   (based on Stillinger-Weber pair style)
+------------------------------------------------------------------------- */
+
+#include "math.h"
+#include "stdio.h"
+#include "stdlib.h"
+#include "string.h"
+#include "pair_nb3b_harmonic.h"
+#include "atom.h"
+#include "neighbor.h"
+#include "neigh_request.h"
+#include "force.h"
+#include "comm.h"
+#include "memory.h"
+#include "neighbor.h"
+#include "neigh_list.h"
+#include "memory.h"
+#include "error.h"
+
+using namespace LAMMPS_NS;
+
+#define MAXLINE 1024
+#define DELTA 4
+#define SMALL 0.001
+#define PI 3.141592653589793238462643383279 
+
+/* ---------------------------------------------------------------------- */
+
+PairNb3bHarmonic::PairNb3bHarmonic(LAMMPS *lmp) : Pair(lmp)
+{
+  single_enable = 0;
+  one_coeff = 1;
+  manybody_flag = 1;
+
+  nelements = 0;
+  elements = NULL;
+  nparams = maxparam = 0;
+  params = NULL;
+  elem2param = NULL;
+}
+
+/* ----------------------------------------------------------------------
+   check if allocated, since class can be destructed when incomplete
+------------------------------------------------------------------------- */
+
+PairNb3bHarmonic::~PairNb3bHarmonic()
+{
+  if (elements)
+    for (int i = 0; i < nelements; i++) delete [] elements[i];
+  delete [] elements;
+  memory->destroy(params);
+  memory->destroy(elem2param);
+
+  if (allocated) {
+    memory->destroy(setflag);
+    memory->destroy(cutsq);
+    delete [] map;
+  }
+}
+
+/* ---------------------------------------------------------------------- */
+
+void PairNb3bHarmonic::compute(int eflag, int vflag)
+{
+  int i,j,k,ii,jj,kk,inum,jnum,jnumm1,itag,jtag;
+  int itype,jtype,ktype,ijparam,ikparam,ijkparam;
+  double xtmp,ytmp,ztmp,delx,dely,delz,evdwl,fpair;
+  double rsq,rsq1,rsq2;
+  double delr1[3],delr2[3],fj[3],fk[3];
+  int *ilist,*jlist,*numneigh,**firstneigh;
+
+  evdwl = 0.0;
+  if (eflag || vflag) ev_setup(eflag,vflag);
+  else evflag = vflag_fdotr = 0;
+
+  double **x = atom->x;
+  double **f = atom->f;
+  int *tag = atom->tag;
+  int *type = atom->type;
+  int nlocal = atom->nlocal;
+  int newton_pair = force->newton_pair;
+
+  inum = list->inum;
+  ilist = list->ilist;
+  numneigh = list->numneigh;
+  firstneigh = list->firstneigh;
+
+  // loop over full neighbor list of my atoms
+
+  for (ii = 0; ii < inum; ii++) {
+    i = ilist[ii];
+    itag = tag[i];
+    itype = map[type[i]];
+    xtmp = x[i][0];
+    ytmp = x[i][1];
+    ztmp = x[i][2];
+
+    // two-body interactions, skip half of them
+
+    jlist = firstneigh[i];
+    jnum = numneigh[i];
+
+    for (jj = 0; jj < jnum; jj++) {
+      j = jlist[jj];
+      j &= NEIGHMASK;
+      jtag = tag[j];
+
+      if (itag > jtag) {
+	if ((itag+jtag) % 2 == 0) continue;
+      } else if (itag < jtag) {
+	if ((itag+jtag) % 2 == 1) continue;
+      } else {
+	if (x[j][2] < ztmp) continue;
+	if (x[j][2] == ztmp && x[j][1] < ytmp) continue;
+	if (x[j][2] == ztmp && x[j][1] == ytmp && x[j][0] < xtmp) continue;
+      }
+
+      jtype = map[type[j]];
+
+      delx = xtmp - x[j][0];
+      dely = ytmp - x[j][1];
+      delz = ztmp - x[j][2];
+      rsq = delx*delx + dely*dely + delz*delz;
+
+      ijparam = elem2param[itype][jtype][jtype];
+      if (rsq > params[ijparam].cutsq) continue;
+
+    }
+
+    jnumm1 = jnum - 1;
+
+    for (jj = 0; jj < jnumm1; jj++) {
+      j = jlist[jj];
+      j &= NEIGHMASK;
+      jtype = map[type[j]];
+      ijparam = elem2param[itype][jtype][jtype];
+      delr1[0] = x[j][0] - xtmp;
+      delr1[1] = x[j][1] - ytmp;
+      delr1[2] = x[j][2] - ztmp;
+      rsq1 = delr1[0]*delr1[0] + delr1[1]*delr1[1] + delr1[2]*delr1[2];
+      if (rsq1 > params[ijparam].cutsq) continue;
+
+      for (kk = jj+1; kk < jnum; kk++) {
+	k = jlist[kk];
+	k &= NEIGHMASK;
+	ktype = map[type[k]];
+	ikparam = elem2param[itype][ktype][ktype];
+	ijkparam = elem2param[itype][jtype][ktype];
+
+	delr2[0] = x[k][0] - xtmp;
+	delr2[1] = x[k][1] - ytmp;
+	delr2[2] = x[k][2] - ztmp;
+	rsq2 = delr2[0]*delr2[0] + delr2[1]*delr2[1] + delr2[2]*delr2[2];
+	if (rsq2 > params[ikparam].cutsq) continue;
+
+        threebody(&params[ijparam],&params[ikparam],&params[ijkparam],
+                  rsq1,rsq2,delr1,delr2,fj,fk,eflag,evdwl);
+
+	f[i][0] -= fj[0] + fk[0];
+	f[i][1] -= fj[1] + fk[1];
+	f[i][2] -= fj[2] + fk[2];
+	f[j][0] += fj[0];
+	f[j][1] += fj[1];
+	f[j][2] += fj[2];
+	f[k][0] += fk[0];
+	f[k][1] += fk[1];
+	f[k][2] += fk[2];
+
+	if (evflag) ev_tally3(i,j,k,evdwl,0.0,fj,fk,delr1,delr2);
+      }
+    }
+  }
+
+  if (vflag_fdotr) virial_fdotr_compute();
+}
+
+/* ---------------------------------------------------------------------- */
+
+void PairNb3bHarmonic::allocate()
+{
+  allocated = 1;
+  int n = atom->ntypes;
+
+  memory->create(setflag,n+1,n+1,"pair:setflag");
+  memory->create(cutsq,n+1,n+1,"pair:cutsq");
+
+  map = new int[n+1];
+}
+
+/* ----------------------------------------------------------------------
+   global settings 
+------------------------------------------------------------------------- */
+
+void PairNb3bHarmonic::settings(int narg, char **arg)
+{
+  if (narg != 0) error->all(FLERR,"Illegal pair_style command");
+}
+
+/* ----------------------------------------------------------------------
+   set coeffs for one or more type pairs
+------------------------------------------------------------------------- */
+
+void PairNb3bHarmonic::coeff(int narg, char **arg)
+{
+  int i,j,n;
+
+  if (!allocated) allocate();
+
+  if (narg != 3 + atom->ntypes)
+    error->all(FLERR,"Incorrect args for pair coefficients");
+
+  // insure I,J args are * *
+
+  if (strcmp(arg[0],"*") != 0 || strcmp(arg[1],"*") != 0)
+    error->all(FLERR,"Incorrect args for pair coefficients");
+
+  // read args that map atom types to elements in potential file
+  // map[i] = which element the Ith atom type is, -1 if NULL
+  // nelements = # of unique elements
+  // elements = list of element names
+
+  if (elements) {
+    for (i = 0; i < nelements; i++) delete [] elements[i];
+    delete [] elements;
+  }
+  elements = new char*[atom->ntypes];
+  for (i = 0; i < atom->ntypes; i++) elements[i] = NULL;
+
+  nelements = 0;
+  for (i = 3; i < narg; i++) {
+    if (strcmp(arg[i],"NULL") == 0) {
+      map[i-2] = -1;
+      continue;
+    }
+    for (j = 0; j < nelements; j++)
+      if (strcmp(arg[i],elements[j]) == 0) break;
+    map[i-2] = j;
+    if (j == nelements) {
+      n = strlen(arg[i]) + 1;
+      elements[j] = new char[n];
+      strcpy(elements[j],arg[i]);
+      nelements++;
+    }
+  }
+
+  // read potential file and initialize potential parameters
+  
+  read_file(arg[2]);
+  setup();
+
+  // clear setflag since coeff() called once with I,J = * *
+
+  n = atom->ntypes;
+  for (int i = 1; i <= n; i++)
+    for (int j = i; j <= n; j++)
+      setflag[i][j] = 0;
+
+  // set setflag i,j for type pairs where both are mapped to elements
+
+  int count = 0;
+  for (int i = 1; i <= n; i++)
+    for (int j = i; j <= n; j++)
+      if (map[i] >= 0 && map[j] >= 0) {
+	setflag[i][j] = 1;
+	count++;
+      }
+
+  if (count == 0) error->all(FLERR,"Incorrect args for pair coefficients");
+}
+
+
+/* ----------------------------------------------------------------------
+   init specific to this pair style
+------------------------------------------------------------------------- */
+
+void PairNb3bHarmonic::init_style()
+{
+  if (atom->tag_enable == 0)
+    error->all(FLERR,"Pair style nb3b/harmonic requires atom IDs");
+  if (force->newton_pair == 0)
+    error->all(FLERR,"Pair style nb3b/harmonic requires newton pair on");
+
+  // need a full neighbor list
+
+  int irequest = neighbor->request(this);
+  neighbor->requests[irequest]->half = 0;
+  neighbor->requests[irequest]->full = 1;
+}
+
+/* ----------------------------------------------------------------------
+   init for one type pair i,j and corresponding j,i
+------------------------------------------------------------------------- */
+
+double PairNb3bHarmonic::init_one(int i, int j)
+{
+  if (setflag[i][j] == 0) error->all(FLERR,"All pair coeffs are not set");
+
+  return cutmax;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void PairNb3bHarmonic::read_file(char *file)
+{
+  int params_per_line = 6;
+  char **words = new char*[params_per_line+1];
+
+  memory->sfree(params);
+  params = NULL;
+  nparams = maxparam = 0;
+
+  // open file on proc 0
+
+  FILE *fp;
+  if (comm->me == 0) {
+    fp = open_potential(file);
+    if (fp == NULL) {
+      char str[128];
+      sprintf(str,"Cannot open nb3b/harmonic potential file %s",file);
+      error->one(FLERR,str);
+    }
+  }
+
+  // read each set of params from potential file
+  // one set of params can span multiple lines
+  // store params if all 3 element tags are in element list
+
+  int n,nwords,ielement,jelement,kelement;
+  char line[MAXLINE],*ptr;
+  int eof = 0;
+
+  while (1) {
+    if (comm->me == 0) {
+      ptr = fgets(line,MAXLINE,fp);
+      if (ptr == NULL) {
+	eof = 1;
+	fclose(fp);
+      } else n = strlen(line) + 1;
+    }
+    MPI_Bcast(&eof,1,MPI_INT,0,world);
+    if (eof) break;
+    MPI_Bcast(&n,1,MPI_INT,0,world);
+    MPI_Bcast(line,n,MPI_CHAR,0,world);
+
+    // strip comment, skip line if blank
+
+    if (ptr = strchr(line,'#')) *ptr = '\0';
+    nwords = atom->count_words(line);
+    if (nwords == 0) continue;
+
+    // concatenate additional lines until have params_per_line words
+
+    while (nwords < params_per_line) {
+      n = strlen(line);
+      if (comm->me == 0) {
+        ptr = fgets(&line[n],MAXLINE-n,fp);
+        if (ptr == NULL) {
+	  eof = 1;
+	  fclose(fp);
+        } else n = strlen(line) + 1;
+      }
+      MPI_Bcast(&eof,1,MPI_INT,0,world);
+      if (eof) break;
+      MPI_Bcast(&n,1,MPI_INT,0,world);
+      MPI_Bcast(line,n,MPI_CHAR,0,world);
+      if (ptr = strchr(line,'#')) *ptr = '\0';
+      nwords = atom->count_words(line);
+    }
+
+    if (nwords != params_per_line)
+      error->all(FLERR,"Incorrect format in nb3b/harmonic potential file");
+
+    // words = ptrs to all words in line
+
+    nwords = 0;
+    words[nwords++] = strtok(line," \t\n\r\f");
+    while (words[nwords++] = strtok(NULL," \t\n\r\f")) continue;
+
+    // ielement,jelement,kelement = 1st args
+    // if all 3 args are in element list, then parse this line
+    // else skip to next entry in file
+
+    for (ielement = 0; ielement < nelements; ielement++)
+      if (strcmp(words[0],elements[ielement]) == 0) break;
+    if (ielement == nelements) continue;
+    for (jelement = 0; jelement < nelements; jelement++)
+      if (strcmp(words[1],elements[jelement]) == 0) break;
+    if (jelement == nelements) continue;
+    for (kelement = 0; kelement < nelements; kelement++)
+      if (strcmp(words[2],elements[kelement]) == 0) break;
+    if (kelement == nelements) continue;
+
+    // load up parameter settings and error check their values
+
+    if (nparams == maxparam) {
+      maxparam += DELTA;
+      params = (Param *) memory->srealloc(params,maxparam*sizeof(Param),
+					  "pair:params");
+    }
+
+    params[nparams].ielement = ielement;
+    params[nparams].jelement = jelement;
+    params[nparams].kelement = kelement;
+    params[nparams].k_theta = atof(words[3]);
+    params[nparams].theta0 = atof(words[4]);
+    params[nparams].cutoff = atof(words[5]);
+
+    if (params[nparams].k_theta < 0.0 || params[nparams].theta0 < 0.0 ||
+        params[nparams].cutoff < 0.0) 
+      error->all(FLERR,"Illegal nb3b/harmonic parameter");
+
+    nparams++;
+  }
+
+  delete [] words;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void PairNb3bHarmonic::setup()
+{
+  int i,j,k,m,n;
+  double rtmp;
+
+  // set elem2param for all triplet combinations
+  // must be a single exact match to lines read from file
+  // do not allow for ACB in place of ABC
+
+  memory->destroy(elem2param);
+  memory->create(elem2param,nelements,nelements,nelements,"pair:elem2param");
+
+  for (i = 0; i < nelements; i++)
+    for (j = 0; j < nelements; j++)
+      for (k = 0; k < nelements; k++) {
+	n = -1;
+	for (m = 0; m < nparams; m++) {
+	  if (i == params[m].ielement && j == params[m].jelement && 
+	      k == params[m].kelement) {
+	    if (n >= 0) error->all(FLERR,"Potential file has duplicate entry");
+	    n = m;
+	  }
+	}
+//	if (n < 0) error->all(FLERR,"Potential file is missing an entry");
+	elem2param[i][j][k] = n;
+      }
+
+  // compute parameter values derived from inputs
+
+  // set cutsq using shortcut to reduce neighbor list for accelerated
+  // calculations. cut must remain unchanged as it is a potential parameter
+  // (cut = a*sigma) 
+
+  for (m = 0; m < nparams; m++) {
+
+    params[m].cut = params[m].cutoff;
+    params[m].cutsq = params[m].cut * params[m].cut;
+
+    params[m].theta0 = params[m].theta0 / 180.0 * PI;
+
+  }
+
+  // set cutmax to max of all params
+
+  cutmax = 0.0;
+  for (m = 0; m < nparams; m++) {
+    rtmp = sqrt(params[m].cutsq);
+    if (rtmp > cutmax) cutmax = rtmp;
+  }
+}  
+
+/* ---------------------------------------------------------------------- */
+
+
+void PairNb3bHarmonic::threebody(Param *paramij, Param *paramik, 
+                                 Param *paramijk,
+                                 double rsq1, double rsq2,
+                                 double *delr1, double *delr2,
+                                 double *fj, double *fk, int eflag, double &eng)
+{
+  double dtheta,tk;
+  double r1,r2,c,s,a,a11,a12,a22;
+
+  // angle (cos and sin)
+  
+  r1 = sqrt(rsq1);
+  r2 = sqrt(rsq2);
+  
+  c = delr1[0]*delr2[0] + delr1[1]*delr2[1] + delr1[2]*delr2[2];
+  c /= r1*r2;
+  
+  if (c > 1.0) c = 1.0;
+  if (c < -1.0) c = -1.0;
+  
+  s = sqrt(1.0 - c*c);
+  if (s < SMALL) s = SMALL;
+  s = 1.0/s;
+  
+  // force & energy
+  
+  dtheta = acos(c) - paramijk->theta0;
+  tk = paramijk->k_theta * dtheta;
+  
+  if (eflag) eng = tk*dtheta;
+  
+  a = -2.0 * tk * s;
+  a11 = a*c / rsq1;
+  a12 = -a / (r1*r2);
+  a22 = a*c / rsq2;
+  
+  fj[0] = a11*delr1[0] + a12*delr2[0];
+  fj[1] = a11*delr1[1] + a12*delr2[1];
+  fj[2] = a11*delr1[2] + a12*delr2[2];
+  fk[0] = a22*delr2[0] + a12*delr1[0];
+  fk[1] = a22*delr2[1] + a12*delr1[1];
+  fk[2] = a22*delr2[2] + a12*delr1[2];
+}
+
diff --git a/src/MANYBODY/pair_nb3b_harmonic.h b/src/MANYBODY/pair_nb3b_harmonic.h
new file mode 100644
index 0000000000..5d126ae09a
--- /dev/null
+++ b/src/MANYBODY/pair_nb3b_harmonic.h
@@ -0,0 +1,64 @@
+/* --*- c++ -*- ---------------------------------------------------------
+   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 PAIR_CLASS
+
+PairStyle(nb3b/harmonic,PairNb3bHarmonic)
+
+#else
+
+#ifndef LMP_PAIR_NB3B_HARMONIC_H
+#define LMP_PAIR_NB3B_HARMONIC_H
+
+#include "pair.h"
+
+namespace LAMMPS_NS {
+
+class PairNb3bHarmonic : public Pair {
+ public:
+  PairNb3bHarmonic(class LAMMPS *);
+  virtual ~PairNb3bHarmonic();
+  virtual void compute(int, int);
+  void settings(int, char **);
+  void coeff(int, char **);
+  double init_one(int, int);
+  void init_style();
+
+ protected:
+  struct Param {
+    double k_theta, theta0, cutoff;
+    double cut,cutsq;
+    int ielement,jelement,kelement;
+  };
+  
+  double cutmax;                // max cutoff for all elements
+  int nelements;                // # of unique elements
+  char **elements;              // names of unique elements
+  int ***elem2param;            // mapping from element triplets to parameters
+  int *map;                     // mapping from atom types to elements
+  int nparams;                  // # of stored parameter sets
+  int maxparam;                 // max # of parameter sets
+  Param *params;                // parameter set for an I-J-K interaction
+
+  void allocate();
+  void read_file(char *);
+  void setup();
+  void twobody(Param *, double, double &, int, double &);
+  void threebody(Param *, Param *, Param *, double, double, double *, double *,
+		 double *, double *, int, double &);
+};
+
+}
+
+#endif
+#endif