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pair_lj_cut_coul_cut_omp.cpp
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Sun, May 26, 18:44

pair_lj_cut_coul_cut_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_lj_cut_coul_cut_omp.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "neighbor.h"
#include "neigh_list.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
PairLJCutCoulCutOMP::PairLJCutCoulCutOMP(LAMMPS *lmp) :
PairLJCutCoulCut(lmp), ThrOMP(lmp, PAIR)
{
respa_enable = 0;
}
/* ---------------------------------------------------------------------- */
void PairLJCutCoulCutOMP::compute(int eflag, int vflag)
{
if (eflag || vflag) {
ev_setup(eflag,vflag);
ev_setup_thr(this);
} else evflag = vflag_fdotr = 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(shared)
#endif
{
int ifrom, ito, tid;
double **f;
f = loop_setup_thr(atom->f, ifrom, ito, tid, inum, nall, nthreads);
if (evflag) {
if (eflag) {
if (force->newton_pair) eval<1,1,1>(f, ifrom, ito, tid);
else eval<1,1,0>(f, ifrom, ito, tid);
} else {
if (force->newton_pair) eval<1,0,1>(f, ifrom, ito, tid);
else eval<1,0,0>(f, ifrom, ito, tid);
}
} else {
if (force->newton_pair) eval<0,0,1>(f, ifrom, ito, tid);
else eval<0,0,0>(f, ifrom, ito, tid);
}
// reduce per thread forces into global force array.
data_reduce_thr(&(atom->f[0][0]), nall, nthreads, 3, tid);
} // end of omp parallel region
// reduce per thread energy and virial, if requested.
if (evflag) ev_reduce_thr(this);
if (vflag_fdotr) virial_fdotr_compute();
}
/* ---------------------------------------------------------------------- */
template <int EVFLAG, int EFLAG, int NEWTON_PAIR>
void PairLJCutCoulCutOMP::eval(double **f, int iifrom, int iito, int tid)
{
int i,j,ii,jj,jnum,itype,jtype;
double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
double rsq,rinv,r2inv,r6inv,forcecoul,forcelj,factor_coul,factor_lj;
int *ilist,*jlist,*numneigh,**firstneigh;
evdwl = ecoul = 0.0;
double **x = atom->x;
double *q = atom->q;
int *type = atom->type;
int nlocal = atom->nlocal;
double *special_coul = force->special_coul;
double *special_lj = force->special_lj;
double qqrd2e = force->qqrd2e;
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];
qtmp = q[i];
xtmp = x[i][0];
ytmp = x[i][1];
ztmp = x[i][2];
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)];
factor_coul = special_coul[sbmask(j)];
j &= NEIGHMASK;
delx = xtmp - x[j][0];
dely = ytmp - x[j][1];
delz = ztmp - x[j][2];
rsq = delx*delx + dely*dely + delz*delz;
jtype = type[j];
if (rsq < cutsq[itype][jtype]) {
r2inv = 1.0/rsq;
if (rsq < cut_coulsq[itype][jtype]) {
rinv = sqrt(r2inv);
forcecoul = qqrd2e * qtmp*q[j]*rinv;
forcecoul *= factor_coul;
} else forcecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
r6inv = r2inv*r2inv*r2inv;
forcelj = r6inv * (lj1[itype][jtype]*r6inv - lj2[itype][jtype]);
forcelj *= factor_lj;
} else forcelj = 0.0;
fpair = (forcecoul + forcelj) * r2inv;
fxtmp += delx*fpair;
fytmp += dely*fpair;
fztmp += delz*fpair;
if (NEWTON_PAIR || j < nlocal) {
f[j][0] -= delx*fpair;
f[j][1] -= dely*fpair;
f[j][2] -= delz*fpair;
}
if (EFLAG) {
if (rsq < cut_coulsq[itype][jtype])
ecoul = factor_coul * qqrd2e * qtmp*q[j]*rinv;
else ecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
evdwl = r6inv*(lj3[itype][jtype]*r6inv-lj4[itype][jtype]) -
offset[itype][jtype];
evdwl *= factor_lj;
}
} else evdwl = 0.0;
if (EVFLAG) ev_tally_thr(this, i,j,nlocal,NEWTON_PAIR,
evdwl,ecoul,fpair,delx,dely,delz,tid);
}
}
f[i][0] += fxtmp;
f[i][1] += fytmp;
f[i][2] += fztmp;
}
}
/* ---------------------------------------------------------------------- */
double PairLJCutCoulCutOMP::memory_usage()
{
double bytes = memory_usage_thr();
bytes += PairLJCutCoulCut::memory_usage();
return bytes;
}

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