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pair_gauss_omp.cpp
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Sat, Nov 9, 15:59

pair_gauss_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_gauss_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;
#define EPSILON 1.0e-10
/* ---------------------------------------------------------------------- */
PairGaussOMP::PairGaussOMP(LAMMPS *lmp) :
PairGauss(lmp), ThrOMP(lmp, THR_PAIR)
{
suffix_flag |= Suffix::OMP;
respa_enable = 0;
}
/* ---------------------------------------------------------------------- */
void PairGaussOMP::compute(int eflag, int vflag)
{
if (eflag || vflag) {
ev_setup(eflag,vflag);
} else evflag = vflag_fdotr = 0;
const int nall = atom->nlocal + atom->nghost;
const int nthreads = comm->nthreads;
const int inum = list->inum;
double occ = 0.0;
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(eflag,vflag) reduction(+:occ)
#endif
{
int ifrom, ito, tid;
loop_setup_thr(ifrom, ito, tid, inum, nthreads);
ThrData *thr = fix->get_thr(tid);
thr->timer(Timer::START);
ev_setup_thr(eflag, vflag, nall, eatom, vatom, thr);
if (evflag) {
if (eflag) {
if (force->newton_pair) occ = eval<1,1,1>(ifrom, ito, thr);
else occ = eval<1,1,0>(ifrom, ito, thr);
} else {
if (force->newton_pair) occ = eval<1,0,1>(ifrom, ito, thr);
else occ = eval<1,0,0>(ifrom, ito, thr);
}
} else {
if (force->newton_pair) occ = eval<0,0,1>(ifrom, ito, thr);
else occ = eval<0,0,0>(ifrom, ito, thr);
}
thr->timer(Timer::PAIR);
reduce_thr(this, eflag, vflag, thr);
} // end of omp parallel region
if (eflag_global) pvector[0] = occ;
}
template <int EVFLAG, int EFLAG, int NEWTON_PAIR>
double PairGaussOMP::eval(int iifrom, int iito, ThrData * const thr)
{
int i,j,ii,jj,jnum,itype,jtype;
double xtmp,ytmp,ztmp,delx,dely,delz,evdwl,fpair;
double rsq,r2inv,forcelj,factor_lj;
int *ilist,*jlist,*numneigh,**firstneigh;
int occ = 0;
evdwl = 0.0;
const dbl3_t * _noalias const x = (dbl3_t *) atom->x[0];
dbl3_t * _noalias const f = (dbl3_t *) thr->get_f()[0];
const int * _noalias const type = atom->type;
const int nlocal = atom->nlocal;
const double * _noalias const special_lj = force->special_lj;
double fxtmp,fytmp,fztmp;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
// loop over neighbors of my atoms
for (ii = iifrom; ii < iito; ++ii) {
i = ilist[ii];
xtmp = x[i].x;
ytmp = x[i].y;
ztmp = x[i].z;
itype = type[i];
jlist = firstneigh[i];
jnum = numneigh[i];
fxtmp=fytmp=fztmp=0.0;
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
factor_lj = special_lj[sbmask(j)];
j &= NEIGHMASK;
delx = xtmp - x[j].x;
dely = ytmp - x[j].y;
delz = ztmp - x[j].z;
rsq = delx*delx + dely*dely + delz*delz;
jtype = type[j];
// define a Gaussian well to be occupied if
// the site it interacts with is within the force maximum
if (EFLAG)
if (eflag_global && rsq < 0.5/b[itype][jtype]) occ++;
if (rsq < cutsq[itype][jtype]) {
r2inv = 1.0/rsq;
forcelj = - 2.0*a[itype][jtype]*b[itype][jtype] * rsq *
exp(-b[itype][jtype]*rsq);
fpair = factor_lj*forcelj*r2inv;
fxtmp += delx*fpair;
fytmp += dely*fpair;
fztmp += delz*fpair;
if (NEWTON_PAIR || j < nlocal) {
f[j].x -= delx*fpair;
f[j].y -= dely*fpair;
f[j].z -= delz*fpair;
}
if (EFLAG) {
evdwl = -(a[itype][jtype]*exp(-b[itype][jtype]*rsq) -
offset[itype][jtype]);
evdwl *= factor_lj;
}
if (EVFLAG) ev_tally_thr(this, i,j,nlocal,NEWTON_PAIR,
evdwl,0.0,fpair,delx,dely,delz,thr);
}
}
f[i].x += fxtmp;
f[i].y += fytmp;
f[i].z += fztmp;
}
return occ;
}
/* ---------------------------------------------------------------------- */
double PairGaussOMP::memory_usage()
{
double bytes = memory_usage_thr();
bytes += PairGauss::memory_usage();
return bytes;
}

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