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pair_tersoff_omp.cpp
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Sat, May 25, 22:54

pair_tersoff_omp.cpp
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
http://lammps.sandia.gov, Sandia National Laboratories
Steve Plimpton, sjplimp@sandia.gov
This software is distributed under the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing author: Axel Kohlmeyer (Temple U)
------------------------------------------------------------------------- */
#include "math.h"
#include "pair_tersoff_omp.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "suffix.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
PairTersoffOMP::PairTersoffOMP(LAMMPS *lmp) :
PairTersoff(lmp), ThrOMP(lmp, THR_PAIR)
{
suffix_flag |= Suffix::OMP;
respa_enable = 0;
}
/* ---------------------------------------------------------------------- */
void PairTersoffOMP::compute(int eflag, int vflag)
{
if (eflag || vflag) {
ev_setup(eflag,vflag);
} else evflag = vflag_fdotr = vflag_atom = 0;
const int nall = atom->nlocal + atom->nghost;
const int nthreads = comm->nthreads;
const int inum = list->inum;
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(eflag,vflag)
#endif
{
int ifrom, ito, tid;
loop_setup_thr(ifrom, ito, tid, inum, nthreads);
ThrData *thr = fix->get_thr(tid);
ev_setup_thr(eflag, vflag, nall, eatom, vatom, thr);
if (evflag) {
if (eflag) {
if (vflag_atom) eval<1,1,1>(ifrom, ito, thr);
else eval<1,1,0>(ifrom, ito, thr);
} else {
if (vflag_atom) eval<1,0,1>(ifrom, ito, thr);
else eval<1,0,0>(ifrom, ito, thr);
}
} else eval<0,0,0>(ifrom, ito, thr);
reduce_thr(this, eflag, vflag, thr);
} // end of omp parallel region
}
template <int EVFLAG, int EFLAG, int VFLAG_ATOM>
void PairTersoffOMP::eval(int iifrom, int iito, ThrData * const thr)
{
int i,j,k,ii,jj,kk,jnum;
int itag,jtag,itype,jtype,ktype,iparam_ij,iparam_ijk;
double xtmp,ytmp,ztmp,delx,dely,delz,evdwl,fpair;
double rsq,rsq1,rsq2;
double delr1[3],delr2[3],fi[3],fj[3],fk[3];
double zeta_ij,prefactor;
int *ilist,*jlist,*numneigh,**firstneigh;
evdwl = 0.0;
const double * const * const x = atom->x;
double * const * const f = thr->get_f();
const int * const tag = atom->tag;
const int * const type = atom->type;
const int nlocal = atom->nlocal;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
double fxtmp,fytmp,fztmp;
// loop over full neighbor list of my atoms
for (ii = iifrom; ii < iito; ++ii) {
i = ilist[ii];
itag = tag[i];
itype = map[type[i]];
xtmp = x[i][0];
ytmp = x[i][1];
ztmp = x[i][2];
fxtmp = fytmp = fztmp = 0.0;
// 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;
iparam_ij = elem2param[itype][jtype][jtype];
if (rsq > params[iparam_ij].cutsq) continue;
repulsive(&params[iparam_ij],rsq,fpair,EFLAG,evdwl);
fxtmp += delx*fpair;
fytmp += dely*fpair;
fztmp += delz*fpair;
f[j][0] -= delx*fpair;
f[j][1] -= dely*fpair;
f[j][2] -= delz*fpair;
if (EVFLAG) ev_tally_thr(this,i,j,nlocal,/* newton_pair */ 1,
evdwl,0.0,fpair,delx,dely,delz,thr);
}
// three-body interactions
// skip immediately if I-J is not within cutoff
double fjxtmp,fjytmp,fjztmp;
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
j &= NEIGHMASK;
jtype = map[type[j]];
iparam_ij = 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[iparam_ij].cutsq) continue;
// accumulate bondorder zeta for each i-j interaction via loop over k
fjxtmp = fjytmp = fjztmp = 0.0;
zeta_ij = 0.0;
for (kk = 0; kk < jnum; kk++) {
if (jj == kk) continue;
k = jlist[kk];
k &= NEIGHMASK;
ktype = map[type[k]];
iparam_ijk = 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[iparam_ijk].cutsq) continue;
zeta_ij += zeta(&params[iparam_ijk],rsq1,rsq2,delr1,delr2);
}
// pairwise force due to zeta
force_zeta(&params[iparam_ij],rsq1,zeta_ij,fpair,prefactor,EFLAG,evdwl);
fxtmp += delr1[0]*fpair;
fytmp += delr1[1]*fpair;
fztmp += delr1[2]*fpair;
fjxtmp -= delr1[0]*fpair;
fjytmp -= delr1[1]*fpair;
fjztmp -= delr1[2]*fpair;
if (EVFLAG) ev_tally_thr(this,i,j,nlocal,/* newton_pair */ 1,evdwl,0.0,
-fpair,-delr1[0],-delr1[1],-delr1[2],thr);
// attractive term via loop over k
for (kk = 0; kk < jnum; kk++) {
if (jj == kk) continue;
k = jlist[kk];
k &= NEIGHMASK;
ktype = map[type[k]];
iparam_ijk = 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[iparam_ijk].cutsq) continue;
attractive(&params[iparam_ijk],prefactor,
rsq1,rsq2,delr1,delr2,fi,fj,fk);
fxtmp += fi[0];
fytmp += fi[1];
fztmp += fi[2];
fjxtmp += fj[0];
fjytmp += fj[1];
fjztmp += fj[2];
f[k][0] += fk[0];
f[k][1] += fk[1];
f[k][2] += fk[2];
if (VFLAG_ATOM) v_tally3_thr(i,j,k,fj,fk,delr1,delr2,thr);
}
f[j][0] += fjxtmp;
f[j][1] += fjytmp;
f[j][2] += fjztmp;
}
f[i][0] += fxtmp;
f[i][1] += fytmp;
f[i][2] += fztmp;
}
}
/* ---------------------------------------------------------------------- */
double PairTersoffOMP::memory_usage()
{
double bytes = memory_usage_thr();
bytes += PairTersoff::memory_usage();
return bytes;
}

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