/* ----------------------------------------------------------------------
   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 authors: Stan Moore (SNL)
------------------------------------------------------------------------- */

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "kokkos.h"
#include "pair_kokkos.h"
#include "pair_eam_fs_kokkos.h"
#include "atom_kokkos.h"
#include "force.h"
#include "comm.h"
#include "neighbor.h"
#include "neigh_list_kokkos.h"
#include "neigh_request.h"
#include "memory.h"
#include "error.h"
#include "atom_masks.h"

using namespace LAMMPS_NS;

#define MAXLINE 1024

// Cannot use virtual inheritance on the GPU, so must duplicate code

/* ---------------------------------------------------------------------- */

template<class DeviceType>
PairEAMFSKokkos<DeviceType>::PairEAMFSKokkos(LAMMPS *lmp) : PairEAM(lmp)
{
  one_coeff = 1;
  manybody_flag = 1;
  respa_enable = 0;

  atomKK = (AtomKokkos *) atom;
  execution_space = ExecutionSpaceFromDevice<DeviceType>::space;
  datamask_read = X_MASK | F_MASK | TYPE_MASK | ENERGY_MASK | VIRIAL_MASK;
  datamask_modify = F_MASK | ENERGY_MASK | VIRIAL_MASK;
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
PairEAMFSKokkos<DeviceType>::~PairEAMFSKokkos()
{
  if (!copymode) {
    memory->destroy_kokkos(k_eatom,eatom);
    memory->destroy_kokkos(k_vatom,vatom);
  }
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::compute(int eflag_in, int vflag_in)
{
  eflag = eflag_in;
  vflag = vflag_in;

  if (neighflag == FULL) no_virial_fdotr_compute = 1;

  if (eflag || vflag) ev_setup(eflag,vflag,0);
  else evflag = vflag_fdotr = 0;

  // reallocate per-atom arrays if necessary

  if (eflag_atom) {
    memory->destroy_kokkos(k_eatom,eatom);
    memory->create_kokkos(k_eatom,eatom,maxeatom,"pair:eatom");
    d_eatom = k_eatom.view<DeviceType>();
  }
  if (vflag_atom) {
    memory->destroy_kokkos(k_vatom,vatom);
    memory->create_kokkos(k_vatom,vatom,maxvatom,6,"pair:vatom");
    d_vatom = k_vatom.view<DeviceType>();
  }

  atomKK->sync(execution_space,datamask_read);
  if (eflag || vflag) atomKK->modified(execution_space,datamask_modify);
  else atomKK->modified(execution_space,F_MASK);

  // grow energy and fp arrays if necessary
  // need to be atom->nmax in length

  if (atom->nmax > nmax) {
    nmax = atom->nmax;
    k_rho = DAT::tdual_ffloat_1d("pair:rho",nmax);
    k_fp = DAT::tdual_ffloat_1d("pair:fp",nmax);
    d_rho = k_rho.template view<DeviceType>();
    d_fp = k_fp.template view<DeviceType>();
    h_rho = k_rho.h_view;
    h_fp = k_fp.h_view;
  }

  x = atomKK->k_x.view<DeviceType>();
  f = atomKK->k_f.view<DeviceType>();
  v_rho = k_rho.view<DeviceType>();
  type = atomKK->k_type.view<DeviceType>();
  tag = atomKK->k_tag.view<DeviceType>();
  nlocal = atom->nlocal;
  nall = atom->nlocal + atom->nghost;
  newton_pair = force->newton_pair;

  NeighListKokkos<DeviceType>* k_list = static_cast<NeighListKokkos<DeviceType>*>(list);
  d_numneigh = k_list->d_numneigh;
  d_neighbors = k_list->d_neighbors;
  d_ilist = k_list->d_ilist;
  int inum = list->inum;

  copymode = 1;

  // zero out density

  if (newton_pair)
    Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSInitialize>(0,nall),*this);
  else
    Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSInitialize>(0,nlocal),*this);

  // loop over neighbors of my atoms

  EV_FLOAT ev;

  // compute kernel A

  if (neighflag == HALF || neighflag == HALFTHREAD) {

    if (neighflag == HALF) {
      if (newton_pair) {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelA<HALF,1> >(0,inum),*this);
      } else {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelA<HALF,0> >(0,inum),*this);
      }
    } else if (neighflag == HALFTHREAD) {
      if (newton_pair) {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelA<HALFTHREAD,1> >(0,inum),*this);
      } else {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelA<HALFTHREAD,0> >(0,inum),*this);
      }
    }

    // communicate and sum densities (on the host)

    if (newton_pair) {
      k_rho.template modify<DeviceType>();
      k_rho.template sync<LMPHostType>();
      comm->reverse_comm_pair(this);
      k_rho.template modify<LMPHostType>();
      k_rho.template sync<DeviceType>();
    }

    // compute kernel B

    if (eflag)
      Kokkos::parallel_reduce(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelB<1> >(0,inum),*this,ev);
    else
      Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelB<0> >(0,inum),*this);

  } else if (neighflag == FULL) {

    // compute kernel AB

    if (eflag)
      Kokkos::parallel_reduce(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelAB<1> >(0,inum),*this,ev);
    else
      Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelAB<0> >(0,inum),*this);
  }

  if (eflag) {
    eng_vdwl += ev.evdwl;
    ev.evdwl = 0.0;
  }

  // communicate derivative of embedding function (on the device)

  comm->forward_comm_pair(this);

  // compute kernel C

  if (evflag) {
    if (neighflag == HALF) {
      if (newton_pair) {
        Kokkos::parallel_reduce(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<HALF,1,1> >(0,inum),*this,ev);
      } else {
        Kokkos::parallel_reduce(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<HALF,0,1> >(0,inum),*this,ev);
      }
    } else if (neighflag == HALFTHREAD) {
      if (newton_pair) {
        Kokkos::parallel_reduce(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<HALFTHREAD,1,1> >(0,inum),*this,ev);
      } else {
        Kokkos::parallel_reduce(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<HALFTHREAD,0,1> >(0,inum),*this,ev);
      }
    } else if (neighflag == FULL) {
      if (newton_pair) {
        Kokkos::parallel_reduce(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<FULL,1,1> >(0,inum),*this,ev);
      } else {
        Kokkos::parallel_reduce(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<FULL,0,1> >(0,inum),*this,ev);
      }
    }
  } else {
    if (neighflag == HALF) {
      if (newton_pair) {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<HALF,1,0> >(0,inum),*this);
      } else {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<HALF,0,0> >(0,inum),*this);
      }
    } else if (neighflag == HALFTHREAD) {
      if (newton_pair) {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<HALFTHREAD,1,0> >(0,inum),*this);
      } else {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<HALFTHREAD,0,0> >(0,inum),*this);
      }
    } else if (neighflag == FULL) {
      if (newton_pair) {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<FULL,1,0> >(0,inum),*this);
      } else {
        Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSKernelC<FULL,0,0> >(0,inum),*this);
      }
    }
  }

  if (eflag_global) eng_vdwl += ev.evdwl;
  if (vflag_global) {
    virial[0] += ev.v[0];
    virial[1] += ev.v[1];
    virial[2] += ev.v[2];
    virial[3] += ev.v[3];
    virial[4] += ev.v[4];
    virial[5] += ev.v[5];
  }

  if (vflag_fdotr) pair_virial_fdotr_compute(this);

  if (eflag_atom) {
    k_eatom.template modify<DeviceType>();
    k_eatom.template sync<LMPHostType>();
  }

  if (vflag_atom) {
    k_vatom.template modify<DeviceType>();
    k_vatom.template sync<LMPHostType>();
  }

  copymode = 0;
}

/* ----------------------------------------------------------------------
   init specific to this pair style
------------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::init_style()
{
  // convert read-in file(s) to arrays and spline them

  PairEAM::init_style();

  // irequest = neigh request made by parent class

  neighflag = lmp->kokkos->neighflag;
  int irequest = neighbor->nrequest - 1;

  neighbor->requests[irequest]->
    kokkos_host = Kokkos::Impl::is_same<DeviceType,LMPHostType>::value &&
    !Kokkos::Impl::is_same<DeviceType,LMPDeviceType>::value;
  neighbor->requests[irequest]->
    kokkos_device = Kokkos::Impl::is_same<DeviceType,LMPDeviceType>::value;

  if (neighflag == FULL) {
    neighbor->requests[irequest]->full = 1;
    neighbor->requests[irequest]->half = 0;
  } else if (neighflag == HALF || neighflag == HALFTHREAD) {
    neighbor->requests[irequest]->full = 0;
    neighbor->requests[irequest]->half = 1;
  } else {
    error->all(FLERR,"Cannot use chosen neighbor list style with pair eam/kk/fs");
  }

}

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::file2array()
{
  file2array_fs();

  int i,j;
  int n = atom->ntypes;

  DAT::tdual_int_1d k_type2frho = DAT::tdual_int_1d("pair:type2frho",n+1);
  DAT::tdual_int_2d k_type2rhor = DAT::tdual_int_2d("pair:type2rhor",n+1,n+1);
  DAT::tdual_int_2d k_type2z2r = DAT::tdual_int_2d("pair:type2z2r",n+1,n+1);

  HAT::t_int_1d h_type2frho =  k_type2frho.h_view;
  HAT::t_int_2d h_type2rhor = k_type2rhor.h_view;
  HAT::t_int_2d h_type2z2r = k_type2z2r.h_view;

  for (i = 1; i <= n; i++) {
    h_type2frho[i] = type2frho[i];
    for (j = 1; j <= n; j++) {
      h_type2rhor(i,j) = type2rhor[i][j];
      h_type2z2r(i,j) = type2z2r[i][j];
    }
  }
  k_type2frho.template modify<LMPHostType>();
  k_type2frho.template sync<DeviceType>();
  k_type2rhor.template modify<LMPHostType>();
  k_type2rhor.template sync<DeviceType>();
  k_type2z2r.template modify<LMPHostType>();
  k_type2z2r.template sync<DeviceType>();

  d_type2frho = k_type2frho.template view<DeviceType>();
  d_type2rhor = k_type2rhor.template view<DeviceType>();
  d_type2z2r = k_type2z2r.template view<DeviceType>();
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::array2spline()
{
  rdr = 1.0/dr;
  rdrho = 1.0/drho;

  tdual_ffloat_2d_n7 k_frho_spline = tdual_ffloat_2d_n7("pair:frho",nfrho,nrho+1);
  tdual_ffloat_2d_n7 k_rhor_spline = tdual_ffloat_2d_n7("pair:rhor",nrhor,nr+1);
  tdual_ffloat_2d_n7 k_z2r_spline = tdual_ffloat_2d_n7("pair:z2r",nz2r,nr+1);

  t_host_ffloat_2d_n7 h_frho_spline = k_frho_spline.h_view;
  t_host_ffloat_2d_n7 h_rhor_spline = k_rhor_spline.h_view;
  t_host_ffloat_2d_n7 h_z2r_spline = k_z2r_spline.h_view;

  for (int i = 0; i < nfrho; i++)
    interpolate(nrho,drho,frho[i],h_frho_spline,i);
  k_frho_spline.template modify<LMPHostType>();
  k_frho_spline.template sync<DeviceType>();

  for (int i = 0; i < nrhor; i++)
    interpolate(nr,dr,rhor[i],h_rhor_spline,i);
  k_rhor_spline.template modify<LMPHostType>();
  k_rhor_spline.template sync<DeviceType>();

  for (int i = 0; i < nz2r; i++)
    interpolate(nr,dr,z2r[i],h_z2r_spline,i);
  k_z2r_spline.template modify<LMPHostType>();
  k_z2r_spline.template sync<DeviceType>();

  d_frho_spline = k_frho_spline.template view<DeviceType>();
  d_rhor_spline = k_rhor_spline.template view<DeviceType>();
  d_z2r_spline = k_z2r_spline.template view<DeviceType>();
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::interpolate(int n, double delta, double *f, t_host_ffloat_2d_n7 h_spline, int i)
{
  for (int m = 1; m <= n; m++) h_spline(i,m,6) = f[m];

  h_spline(i,1,5) = h_spline(i,2,6) - h_spline(i,1,6);
  h_spline(i,2,5) = 0.5 * (h_spline(i,3,6)-h_spline(i,1,6));
  h_spline(i,n-1,5) = 0.5 * (h_spline(i,n,6)-h_spline(i,n-2,6));
  h_spline(i,n,5) = h_spline(i,n,6) - h_spline(i,n-1,6);

  for (int m = 3; m <= n-2; m++)
    h_spline(i,m,5) = ((h_spline(i,m-2,6)-h_spline(i,m+2,6)) +
                    8.0*(h_spline(i,m+1,6)-h_spline(i,m-1,6))) / 12.0;

  for (int m = 1; m <= n-1; m++) {
    h_spline(i,m,4) = 3.0*(h_spline(i,m+1,6)-h_spline(i,m,6)) -
      2.0*h_spline(i,m,5) - h_spline(i,m+1,5);
    h_spline(i,m,3) = h_spline(i,m,5) + h_spline(i,m+1,5) -
      2.0*(h_spline(i,m+1,6)-h_spline(i,m,6));
  }

  h_spline(i,n,4) = 0.0;
  h_spline(i,n,3) = 0.0;

  for (int m = 1; m <= n; m++) {
    h_spline(i,m,2) = h_spline(i,m,5)/delta;
    h_spline(i,m,1) = 2.0*h_spline(i,m,4)/delta;
    h_spline(i,m,0) = 3.0*h_spline(i,m,3)/delta;
  }
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
int PairEAMFSKokkos<DeviceType>::pack_forward_comm_kokkos(int n, DAT::tdual_int_2d k_sendlist, int iswap_in, DAT::tdual_xfloat_1d &buf,
                               int pbc_flag, int *pbc)
{
  d_sendlist = k_sendlist.view<DeviceType>();
  iswap = iswap_in;
  v_buf = buf.view<DeviceType>();
  Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSPackForwardComm>(0,n),*this);
  return n;
}

template<class DeviceType>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSPackForwardComm, const int &i) const {
  int j = d_sendlist(iswap, i);
  v_buf[i] = d_fp[j];
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::unpack_forward_comm_kokkos(int n, int first_in, DAT::tdual_xfloat_1d &buf)
{
  first = first_in;
  v_buf = buf.view<DeviceType>();
  Kokkos::parallel_for(Kokkos::RangePolicy<DeviceType, TagPairEAMFSUnpackForwardComm>(0,n),*this);
}

template<class DeviceType>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSUnpackForwardComm, const int &i) const {
  d_fp[i + first] = v_buf[i];
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
int PairEAMFSKokkos<DeviceType>::pack_forward_comm(int n, int *list, double *buf,
                               int pbc_flag, int *pbc)
{
  int i,j;

  for (i = 0; i < n; i++) {
    j = list[i];
    buf[i] = h_fp[j];
  }
  return n;
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::unpack_forward_comm(int n, int first, double *buf)
{
  for (int i = 0; i < n; i++) {
    h_fp[i + first] = buf[i];
  }
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
int PairEAMFSKokkos<DeviceType>::pack_reverse_comm(int n, int first, double *buf)
{
  int i,m,last;

  m = 0;
  last = first + n;
  for (i = first; i < last; i++) buf[m++] = h_rho[i];
  return m;
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::unpack_reverse_comm(int n, int *list, double *buf)
{
  int i,j,m;

  m = 0;
  for (i = 0; i < n; i++) {
    j = list[i];
    h_rho[j] += buf[m++];
  }
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSInitialize, const int &i) const {
  d_rho[i] = 0.0;
}

/* ---------------------------------------------------------------------- */

////Specialisation for Neighborlist types Half, HalfThread, Full
template<class DeviceType>
template<int NEIGHFLAG, int NEWTON_PAIR>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSKernelA<NEIGHFLAG,NEWTON_PAIR>, const int &ii) const {

  // rho = density at each atom
  // loop over neighbors of my atoms

  // The rho array is atomic for Half/Thread neighbor style
  Kokkos::View<F_FLOAT*, typename DAT::t_f_array::array_layout,DeviceType,Kokkos::MemoryTraits<AtomicF<NEIGHFLAG>::value> > rho = v_rho;

  const int i = d_ilist[ii];
  const X_FLOAT xtmp = x(i,0);
  const X_FLOAT ytmp = x(i,1);
  const X_FLOAT ztmp = x(i,2);
  const int itype = type(i);

  //const AtomNeighborsConst d_neighbors_i = k_list.get_neighbors_const(i);
  const int jnum = d_numneigh[i];

  F_FLOAT rhotmp = 0.0;

  for (int jj = 0; jj < jnum; jj++) {
    //int j = d_neighbors_i[jj];
    int j = d_neighbors(i,jj);
    j &= NEIGHMASK;
    const X_FLOAT delx = xtmp - x(j,0);
    const X_FLOAT dely = ytmp - x(j,1);
    const X_FLOAT delz = ztmp - x(j,2);
    const int jtype = type(j);
    const F_FLOAT rsq = delx*delx + dely*dely + delz*delz;

    if (rsq < cutforcesq) {
      F_FLOAT p = sqrt(rsq)*rdr + 1.0;
      int m = static_cast<int> (p);
      m = MIN(m,nr-1);
      p -= m;
      p = MIN(p,1.0);
      const int d_type2rhor_ji = d_type2rhor(jtype,itype);
      rhotmp += ((d_rhor_spline(d_type2rhor_ji,m,3)*p + d_rhor_spline(d_type2rhor_ji,m,4))*p +
                  d_rhor_spline(d_type2rhor_ji,m,5))*p + d_rhor_spline(d_type2rhor_ji,m,6);
      if (NEWTON_PAIR || j < nlocal) {
        const int d_type2rhor_ij = d_type2rhor(itype,jtype);
        rho[j] += ((d_rhor_spline(d_type2rhor_ij,m,3)*p + d_rhor_spline(d_type2rhor_ij,m,4))*p +
                    d_rhor_spline(d_type2rhor_ij,m,5))*p + d_rhor_spline(d_type2rhor_ij,m,6);
      }
    }

  }
  rho[i] += rhotmp;
}

/* ---------------------------------------------------------------------- */

////Specialisation for Neighborlist types Half, HalfThread, Full
template<class DeviceType>
template<int EFLAG>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSKernelB<EFLAG>, const int &ii, EV_FLOAT& ev) const {

  // fp = derivative of embedding energy at each atom
  // phi = embedding energy at each atom
  // if rho > rhomax (e.g. due to close approach of two atoms),
  //   will exceed table, so add linear term to conserve energy

  const int i = d_ilist[ii];
  const int itype = type(i);

  F_FLOAT p = d_rho[i]*rdrho + 1.0;
  int m = static_cast<int> (p);
  m = MAX(1,MIN(m,nrho-1));
  p -= m;
  p = MIN(p,1.0);
  const int d_type2frho_i = d_type2frho[itype];
  d_fp[i] = (d_frho_spline(d_type2frho_i,m,0)*p + d_frho_spline(d_type2frho_i,m,1))*p + d_frho_spline(d_type2frho_i,m,2);
  if (EFLAG) {
    F_FLOAT phi = ((d_frho_spline(d_type2frho_i,m,3)*p + d_frho_spline(d_type2frho_i,m,4))*p +
                    d_frho_spline(d_type2frho_i,m,5))*p + d_frho_spline(d_type2frho_i,m,6);
    if (d_rho[i] > rhomax) phi += d_fp[i] * (d_rho[i]-rhomax);
    if (eflag_global) ev.evdwl += phi;
    if (eflag_atom) d_eatom[i] += phi;
  }

}

template<class DeviceType>
template<int EFLAG>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSKernelB<EFLAG>, const int &ii) const {
  EV_FLOAT ev;
  this->template operator()<EFLAG>(TagPairEAMFSKernelB<EFLAG>(), ii, ev);
}

/* ---------------------------------------------------------------------- */

////Specialisation for Neighborlist types Half, HalfThread, Full
template<class DeviceType>
template<int EFLAG>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSKernelAB<EFLAG>, const int &ii, EV_FLOAT& ev) const {

  // rho = density at each atom
  // loop over neighbors of my atoms

  const int i = d_ilist[ii];
  const X_FLOAT xtmp = x(i,0);
  const X_FLOAT ytmp = x(i,1);
  const X_FLOAT ztmp = x(i,2);
  const int itype = type(i);

  //const AtomNeighborsConst d_neighbors_i = k_list.get_neighbors_const(i);
  const int jnum = d_numneigh[i];

  F_FLOAT rhotmp = 0.0;

  for (int jj = 0; jj < jnum; jj++) {
    //int j = d_neighbors_i[jj];
    int j = d_neighbors(i,jj);
    j &= NEIGHMASK;
    const X_FLOAT delx = xtmp - x(j,0);
    const X_FLOAT dely = ytmp - x(j,1);
    const X_FLOAT delz = ztmp - x(j,2);
    const int jtype = type(j);
    const F_FLOAT rsq = delx*delx + dely*dely + delz*delz;

    if (rsq < cutforcesq) {
      F_FLOAT p = sqrt(rsq)*rdr + 1.0;
      int m = static_cast<int> (p);
      m = MIN(m,nr-1);
      p -= m;
      p = MIN(p,1.0);
      const int d_type2rhor_ji = d_type2rhor(jtype,itype);
      rhotmp += ((d_rhor_spline(d_type2rhor_ji,m,3)*p + d_rhor_spline(d_type2rhor_ji,m,4))*p +
                  d_rhor_spline(d_type2rhor_ji,m,5))*p + d_rhor_spline(d_type2rhor_ji,m,6);
    }

  }
  d_rho[i] += rhotmp;

  // fp = derivative of embedding energy at each atom
  // phi = embedding energy at each atom
  // if rho > rhomax (e.g. due to close approach of two atoms),
  //   will exceed table, so add linear term to conserve energy

  F_FLOAT p = d_rho[i]*rdrho + 1.0;
  int m = static_cast<int> (p);
  m = MAX(1,MIN(m,nrho-1));
  p -= m;
  p = MIN(p,1.0);
  const int d_type2frho_i = d_type2frho[itype];
  d_fp[i] = (d_frho_spline(d_type2frho_i,m,0)*p + d_frho_spline(d_type2frho_i,m,1))*p + d_frho_spline(d_type2frho_i,m,2);
  if (EFLAG) {
    F_FLOAT phi = ((d_frho_spline(d_type2frho_i,m,3)*p + d_frho_spline(d_type2frho_i,m,4))*p +
                    d_frho_spline(d_type2frho_i,m,5))*p + d_frho_spline(d_type2frho_i,m,6);
    if (d_rho[i] > rhomax) phi += d_fp[i] * (d_rho[i]-rhomax);
    if (eflag_global) ev.evdwl += phi;
    if (eflag_atom) d_eatom[i] += phi;
  }

}

template<class DeviceType>
template<int EFLAG>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSKernelAB<EFLAG>, const int &ii) const {
  EV_FLOAT ev;
  this->template operator()<EFLAG>(TagPairEAMFSKernelAB<EFLAG>(), ii, ev);
}

/* ---------------------------------------------------------------------- */

////Specialisation for Neighborlist types Half, HalfThread, Full
template<class DeviceType>
template<int NEIGHFLAG, int NEWTON_PAIR, int EVFLAG>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSKernelC<NEIGHFLAG,NEWTON_PAIR,EVFLAG>, const int &ii, EV_FLOAT& ev) const {

  // The f array is atomic for Half/Thread neighbor style
  Kokkos::View<F_FLOAT*[3], typename DAT::t_f_array::array_layout,DeviceType,Kokkos::MemoryTraits<AtomicF<NEIGHFLAG>::value> > a_f = f;

  const int i = d_ilist[ii];
  const X_FLOAT xtmp = x(i,0);
  const X_FLOAT ytmp = x(i,1);
  const X_FLOAT ztmp = x(i,2);
  const int itype = type(i);

  //const AtomNeighborsConst d_neighbors_i = k_list.get_neighbors_const(i);
  const int jnum = d_numneigh[i];

  F_FLOAT fxtmp = 0.0;
  F_FLOAT fytmp = 0.0;
  F_FLOAT fztmp = 0.0;

  for (int jj = 0; jj < jnum; jj++) {
    //int j = d_neighbors_i[jj];
    int j = d_neighbors(i,jj);
    j &= NEIGHMASK;
    const X_FLOAT delx = xtmp - x(j,0);
    const X_FLOAT dely = ytmp - x(j,1);
    const X_FLOAT delz = ztmp - x(j,2);
    const int jtype = type(j);
    const F_FLOAT rsq = delx*delx + dely*dely + delz*delz;

    if(rsq < cutforcesq) {
      const F_FLOAT r = sqrt(rsq);
      F_FLOAT p = r*rdr + 1.0;
      int m = static_cast<int> (p);
      m = MIN(m,nr-1);
      p -= m;
      p = MIN(p,1.0);

      // rhoip = derivative of (density at atom j due to atom i)
      // rhojp = derivative of (density at atom i due to atom j)
      // phi = pair potential energy
      // phip = phi'
      // z2 = phi * r
      // z2p = (phi * r)' = (phi' r) + phi
      // psip needs both fp[i] and fp[j] terms since r_ij appears in two
      //   terms of embed eng: Fi(sum rho_ij) and Fj(sum rho_ji)
      //   hence embed' = Fi(sum rho_ij) rhojp + Fj(sum rho_ji) rhoip

      const int d_type2rhor_ij = d_type2rhor(itype,jtype);
      const F_FLOAT rhoip = (d_rhor_spline(d_type2rhor_ij,m,0)*p + d_rhor_spline(d_type2rhor_ij,m,1))*p +
                             d_rhor_spline(d_type2rhor_ij,m,2);
      const int d_type2rhor_ji = d_type2rhor(jtype,itype);
      const F_FLOAT rhojp = (d_rhor_spline(d_type2rhor_ji,m,0)*p + d_rhor_spline(d_type2rhor_ji,m,1))*p +
                             d_rhor_spline(d_type2rhor_ji,m,2);
      const int d_type2z2r_ij = d_type2z2r(itype,jtype);
      const F_FLOAT z2p = (d_z2r_spline(d_type2z2r_ij,m,0)*p + d_z2r_spline(d_type2z2r_ij,m,1))*p +
                           d_z2r_spline(d_type2z2r_ij,m,2);
      const F_FLOAT z2 = ((d_z2r_spline(d_type2z2r_ij,m,3)*p + d_z2r_spline(d_type2z2r_ij,m,4))*p +
                           d_z2r_spline(d_type2z2r_ij,m,5))*p + d_z2r_spline(d_type2z2r_ij,m,6);

      const F_FLOAT recip = 1.0/r;
      const F_FLOAT phi = z2*recip;
      const F_FLOAT phip = z2p*recip - phi*recip;
      const F_FLOAT psip = d_fp[i]*rhojp + d_fp[j]*rhoip + phip;
      const F_FLOAT fpair = -psip*recip;

      fxtmp += delx*fpair;
      fytmp += dely*fpair;
      fztmp += delz*fpair;

      if ((NEIGHFLAG==HALF || NEIGHFLAG==HALFTHREAD) && (NEWTON_PAIR || j < nlocal)) {
        a_f(j,0) -= delx*fpair;
        a_f(j,1) -= dely*fpair;
        a_f(j,2) -= delz*fpair;
      }

      if (EVFLAG) {
        if (eflag) {
          ev.evdwl += (((NEIGHFLAG==HALF || NEIGHFLAG==HALFTHREAD)&&(NEWTON_PAIR||(j<nlocal)))?1.0:0.5)*phi;
        }

        if (vflag_either || eflag_atom) this->template ev_tally<NEIGHFLAG,NEWTON_PAIR>(ev,i,j,phi,fpair,delx,dely,delz);
      }

    }
  }

  a_f(i,0) += fxtmp;
  a_f(i,1) += fytmp;
  a_f(i,2) += fztmp;
}

template<class DeviceType>
template<int NEIGHFLAG, int NEWTON_PAIR, int EVFLAG>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::operator()(TagPairEAMFSKernelC<NEIGHFLAG,NEWTON_PAIR,EVFLAG>, const int &ii) const {
  EV_FLOAT ev;
  this->template operator()<NEIGHFLAG,NEWTON_PAIR,EVFLAG>(TagPairEAMFSKernelC<NEIGHFLAG,NEWTON_PAIR,EVFLAG>(), ii, ev);
}

/* ---------------------------------------------------------------------- */

template<class DeviceType>
template<int NEIGHFLAG, int NEWTON_PAIR>
KOKKOS_INLINE_FUNCTION
void PairEAMFSKokkos<DeviceType>::ev_tally(EV_FLOAT &ev, const int &i, const int &j,
      const F_FLOAT &epair, const F_FLOAT &fpair, const F_FLOAT &delx,
                const F_FLOAT &dely, const F_FLOAT &delz) const
{
  const int EFLAG = eflag;
  const int VFLAG = vflag_either;

  // The eatom and vatom arrays are atomic for Half/Thread neighbor style
  Kokkos::View<E_FLOAT*, typename DAT::t_efloat_1d::array_layout,DeviceType,Kokkos::MemoryTraits<AtomicF<NEIGHFLAG>::value> > v_eatom = k_eatom.view<DeviceType>();
  Kokkos::View<F_FLOAT*[6], typename DAT::t_virial_array::array_layout,DeviceType,Kokkos::MemoryTraits<AtomicF<NEIGHFLAG>::value> > v_vatom = k_vatom.view<DeviceType>();

  if (EFLAG) {
    if (eflag_atom) {
      const E_FLOAT epairhalf = 0.5 * epair;
      if (NEIGHFLAG!=FULL) {
        if (NEWTON_PAIR || i < nlocal) v_eatom[i] += epairhalf;
        if (NEWTON_PAIR || j < nlocal) v_eatom[j] += epairhalf;
      } else {
        v_eatom[i] += epairhalf;
      }
    }
  }

  if (VFLAG) {
    const E_FLOAT v0 = delx*delx*fpair;
    const E_FLOAT v1 = dely*dely*fpair;
    const E_FLOAT v2 = delz*delz*fpair;
    const E_FLOAT v3 = delx*dely*fpair;
    const E_FLOAT v4 = delx*delz*fpair;
    const E_FLOAT v5 = dely*delz*fpair;

    if (vflag_global) {
      if (NEIGHFLAG!=FULL) {
        if (NEWTON_PAIR || i < nlocal) {
          ev.v[0] += 0.5*v0;
          ev.v[1] += 0.5*v1;
          ev.v[2] += 0.5*v2;
          ev.v[3] += 0.5*v3;
          ev.v[4] += 0.5*v4;
          ev.v[5] += 0.5*v5;
        }
        if (NEWTON_PAIR || j < nlocal) {
        ev.v[0] += 0.5*v0;
        ev.v[1] += 0.5*v1;
        ev.v[2] += 0.5*v2;
        ev.v[3] += 0.5*v3;
        ev.v[4] += 0.5*v4;
        ev.v[5] += 0.5*v5;
        }
      } else {
        ev.v[0] += 0.5*v0;
        ev.v[1] += 0.5*v1;
        ev.v[2] += 0.5*v2;
        ev.v[3] += 0.5*v3;
        ev.v[4] += 0.5*v4;
        ev.v[5] += 0.5*v5;
      }
    }

    if (vflag_atom) {
      if (NEIGHFLAG!=FULL) {
        if (NEWTON_PAIR || i < nlocal) {
          v_vatom(i,0) += 0.5*v0;
          v_vatom(i,1) += 0.5*v1;
          v_vatom(i,2) += 0.5*v2;
          v_vatom(i,3) += 0.5*v3;
          v_vatom(i,4) += 0.5*v4;
          v_vatom(i,5) += 0.5*v5;
        }
        if (NEWTON_PAIR || j < nlocal) {
        v_vatom(j,0) += 0.5*v0;
        v_vatom(j,1) += 0.5*v1;
        v_vatom(j,2) += 0.5*v2;
        v_vatom(j,3) += 0.5*v3;
        v_vatom(j,4) += 0.5*v4;
        v_vatom(j,5) += 0.5*v5;
        }
      } else {
        v_vatom(i,0) += 0.5*v0;
        v_vatom(i,1) += 0.5*v1;
        v_vatom(i,2) += 0.5*v2;
        v_vatom(i,3) += 0.5*v3;
        v_vatom(i,4) += 0.5*v4;
        v_vatom(i,5) += 0.5*v5;
      }
    }
  }
}

/* ---------------------------------------------------------------------- */

// Duplicate PairEAMFS functions

/* ----------------------------------------------------------------------
   set coeffs for one or more type pairs
   read EAM Finnis-Sinclair file
------------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::coeff(int narg, char **arg)
{
  int i,j;

  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 EAM Finnis-Sinclair file

  if (fs) {
    for (i = 0; i < fs->nelements; i++) delete [] fs->elements[i];
    delete [] fs->elements;
    delete [] fs->mass;
    memory->destroy(fs->frho);
    memory->destroy(fs->rhor);
    memory->destroy(fs->z2r);
    delete fs;
  }
  fs = new Fs();
  read_file(arg[2]);

  // read args that map atom types to elements in potential file
  // map[i] = which element the Ith atom type is, -1 if NULL

  for (i = 3; i < narg; i++) {
    if (strcmp(arg[i],"NULL") == 0) {
      map[i-2] = -1;
      continue;
    }
    for (j = 0; j < fs->nelements; j++)
      if (strcmp(arg[i],fs->elements[j]) == 0) break;
    if (j < fs->nelements) map[i-2] = j;
    else error->all(FLERR,"No matching element in EAM potential file");
  }

  // clear setflag since coeff() called once with I,J = * *

  int n = atom->ntypes;
  for (i = 1; i <= n; i++)
    for (j = i; j <= n; j++)
      setflag[i][j] = 0;

  // set setflag i,j for type pairs where both are mapped to elements
  // set mass of atom type if i = j

  int count = 0;
  for (i = 1; i <= n; i++) {
    for (j = i; j <= n; j++) {
      if (map[i] >= 0 && map[j] >= 0) {
        setflag[i][j] = 1;
        if (i == j) atom->set_mass(FLERR,i,fs->mass[map[i]]);
        count++;
      }
    }
  }

  if (count == 0) error->all(FLERR,"Incorrect args for pair coefficients");
}

/* ----------------------------------------------------------------------
   read a multi-element DYNAMO setfl file
------------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::read_file(char *filename)
{
  Fs *file = fs;

  // open potential file

  int me = comm->me;
  FILE *fptr;
  char line[MAXLINE];

  if (me == 0) {
    fptr = force->open_potential(filename);
    if (fptr == NULL) {
      char str[128];
      sprintf(str,"Cannot open EAM potential file %s",filename);
      error->one(FLERR,str);
    }
  }

  // read and broadcast header
  // extract element names from nelements line

  int n;
  if (me == 0) {
    fgets(line,MAXLINE,fptr);
    fgets(line,MAXLINE,fptr);
    fgets(line,MAXLINE,fptr);
    fgets(line,MAXLINE,fptr);
    n = strlen(line) + 1;
  }
  MPI_Bcast(&n,1,MPI_INT,0,world);
  MPI_Bcast(line,n,MPI_CHAR,0,world);

  sscanf(line,"%d",&file->nelements);
  int nwords = atom->count_words(line);
  if (nwords != file->nelements + 1)
    error->all(FLERR,"Incorrect element names in EAM potential file");

  char **words = new char*[file->nelements+1];
  nwords = 0;
  strtok(line," \t\n\r\f");
  while ((words[nwords++] = strtok(NULL," \t\n\r\f"))) continue;

  file->elements = new char*[file->nelements];
  for (int i = 0; i < file->nelements; i++) {
    n = strlen(words[i]) + 1;
    file->elements[i] = new char[n];
    strcpy(file->elements[i],words[i]);
  }
  delete [] words;

  if (me == 0) {
    fgets(line,MAXLINE,fptr);
    sscanf(line,"%d %lg %d %lg %lg",
           &file->nrho,&file->drho,&file->nr,&file->dr,&file->cut);
  }

  MPI_Bcast(&file->nrho,1,MPI_INT,0,world);
  MPI_Bcast(&file->drho,1,MPI_DOUBLE,0,world);
  MPI_Bcast(&file->nr,1,MPI_INT,0,world);
  MPI_Bcast(&file->dr,1,MPI_DOUBLE,0,world);
  MPI_Bcast(&file->cut,1,MPI_DOUBLE,0,world);

  file->mass = new double[file->nelements];
  memory->create(file->frho,file->nelements,file->nrho+1,
                                              "pair:frho");
  memory->create(file->rhor,file->nelements,file->nelements,
                 file->nr+1,"pair:rhor");
  memory->create(file->z2r,file->nelements,file->nelements,
                 file->nr+1,"pair:z2r");

  int i,j,tmp;
  for (i = 0; i < file->nelements; i++) {
    if (me == 0) {
      fgets(line,MAXLINE,fptr);
      sscanf(line,"%d %lg",&tmp,&file->mass[i]);
    }
    MPI_Bcast(&file->mass[i],1,MPI_DOUBLE,0,world);

    if (me == 0) grab(fptr,file->nrho,&file->frho[i][1]);
    MPI_Bcast(&file->frho[i][1],file->nrho,MPI_DOUBLE,0,world);

    for (j = 0; j < file->nelements; j++) {
      if (me == 0) grab(fptr,file->nr,&file->rhor[i][j][1]);
      MPI_Bcast(&file->rhor[i][j][1],file->nr,MPI_DOUBLE,0,world);
    }
  }

  for (i = 0; i < file->nelements; i++)
    for (j = 0; j <= i; j++) {
      if (me == 0) grab(fptr,file->nr,&file->z2r[i][j][1]);
      MPI_Bcast(&file->z2r[i][j][1],file->nr,MPI_DOUBLE,0,world);
    }

  // close the potential file

  if (me == 0) fclose(fptr);
}

/* ----------------------------------------------------------------------
   copy read-in setfl potential to standard array format
------------------------------------------------------------------------- */

template<class DeviceType>
void PairEAMFSKokkos<DeviceType>::file2array_fs()
{
  int i,j,m,n;
  int ntypes = atom->ntypes;

  // set function params directly from fs file

  nrho = fs->nrho;
  nr = fs->nr;
  drho = fs->drho;
  dr = fs->dr;
  rhomax = (nrho-1) * drho;

  // ------------------------------------------------------------------
  // setup frho arrays
  // ------------------------------------------------------------------

  // allocate frho arrays
  // nfrho = # of fs elements + 1 for zero array

  nfrho = fs->nelements + 1;
  memory->destroy(frho);
  memory->create(frho,nfrho,nrho+1,"pair:frho");

  // copy each element's frho to global frho

  for (i = 0; i < fs->nelements; i++)
    for (m = 1; m <= nrho; m++) frho[i][m] = fs->frho[i][m];

  // add extra frho of zeroes for non-EAM types to point to (pair hybrid)
  // this is necessary b/c fp is still computed for non-EAM atoms

  for (m = 1; m <= nrho; m++) frho[nfrho-1][m] = 0.0;

  // type2frho[i] = which frho array (0 to nfrho-1) each atom type maps to
  // if atom type doesn't point to element (non-EAM atom in pair hybrid)
  // then map it to last frho array of zeroes

  for (i = 1; i <= ntypes; i++)
    if (map[i] >= 0) type2frho[i] = map[i];
    else type2frho[i] = nfrho-1;

  // ------------------------------------------------------------------
  // setup rhor arrays
  // ------------------------------------------------------------------

  // allocate rhor arrays
  // nrhor = square of # of fs elements

  nrhor = fs->nelements * fs->nelements;
  memory->destroy(rhor);
  memory->create(rhor,nrhor,nr+1,"pair:rhor");

  // copy each element pair rhor to global rhor

  n = 0;
  for (i = 0; i < fs->nelements; i++)
    for (j = 0; j < fs->nelements; j++) {
      for (m = 1; m <= nr; m++) rhor[n][m] = fs->rhor[i][j][m];
      n++;
    }

  // type2rhor[i][j] = which rhor array (0 to nrhor-1) each type pair maps to
  // for fs files, there is a full NxN set of rhor arrays
  // OK if map = -1 (non-EAM atom in pair hybrid) b/c type2rhor not used

  for (i = 1; i <= ntypes; i++)
    for (j = 1; j <= ntypes; j++)
      type2rhor[i][j] = map[i] * fs->nelements + map[j];

  // ------------------------------------------------------------------
  // setup z2r arrays
  // ------------------------------------------------------------------

  // allocate z2r arrays
  // nz2r = N*(N+1)/2 where N = # of fs elements

  nz2r = fs->nelements * (fs->nelements+1) / 2;
  memory->destroy(z2r);
  memory->create(z2r,nz2r,nr+1,"pair:z2r");

  // copy each element pair z2r to global z2r, only for I >= J

  n = 0;
  for (i = 0; i < fs->nelements; i++)
    for (j = 0; j <= i; j++) {
      for (m = 1; m <= nr; m++) z2r[n][m] = fs->z2r[i][j][m];
      n++;
    }

  // type2z2r[i][j] = which z2r array (0 to nz2r-1) each type pair maps to
  // set of z2r arrays only fill lower triangular Nelement matrix
  // value = n = sum over rows of lower-triangular matrix until reach irow,icol
  // swap indices when irow < icol to stay lower triangular
  // if map = -1 (non-EAM atom in pair hybrid):
  //   type2z2r is not used by non-opt
  //   but set type2z2r to 0 since accessed by opt

  int irow,icol;
  for (i = 1; i <= ntypes; i++) {
    for (j = 1; j <= ntypes; j++) {
      irow = map[i];
      icol = map[j];
      if (irow == -1 || icol == -1) {
        type2z2r[i][j] = 0;
        continue;
      }
      if (irow < icol) {
        irow = map[j];
        icol = map[i];
      }
      n = 0;
      for (m = 0; m < irow; m++) n += m + 1;
      n += icol;
      type2z2r[i][j] = n;
    }
  }
}

/* ---------------------------------------------------------------------- */

namespace LAMMPS_NS {
template class PairEAMFSKokkos<LMPDeviceType>;
#ifdef KOKKOS_HAVE_CUDA
template class PairEAMFSKokkos<LMPHostType>;
#endif
}

