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lammps/src/USER-OMP/pair_coul_dsf_omp.cpp
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pair_coul_dsf_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_coul_dsf_omp.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "suffix.h"
#include "math_const.h"
using namespace LAMMPS_NS;
using namespace MathConst;
#define EWALD_F 1.12837917
#define EWALD_P 0.3275911
#define A1 0.254829592
#define A2 -0.284496736
#define A3 1.421413741
#define A4 -1.453152027
#define A5 1.061405429
/* ---------------------------------------------------------------------- */
PairCoulDSFOMP::PairCoulDSFOMP(LAMMPS *lmp) :
PairCoulDSF(lmp), ThrOMP(lmp, THR_PAIR)
{
suffix_flag |= Suffix::OMP;
respa_enable = 0;
}
/* ---------------------------------------------------------------------- */
void PairCoulDSFOMP::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;
#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);
thr->timer(Timer::START);
ev_setup_thr(eflag, vflag, nall, eatom, vatom, thr);
if (evflag) {
if (eflag) {
if (force->newton_pair) eval<1,1,1>(ifrom, ito, thr);
else eval<1,1,0>(ifrom, ito, thr);
} else {
if (force->newton_pair) eval<1,0,1>(ifrom, ito, thr);
else eval<1,0,0>(ifrom, ito, thr);
}
} else {
if (force->newton_pair) eval<0,0,1>(ifrom, ito, thr);
else eval<0,0,0>(ifrom, ito, thr);
}
thr->timer(Timer::PAIR);
reduce_thr(this, eflag, vflag, thr);
} // end of omp parallel region
}
/* ---------------------------------------------------------------------- */
template <int EVFLAG, int EFLAG, int NEWTON_PAIR>
void PairCoulDSFOMP::eval(int iifrom, int iito, ThrData * const thr)
{
int i,j,ii,jj,jnum;
double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,ecoul,fpair;
double r,rsq,r2inv,forcecoul,factor_coul;
double prefactor,erfcc,erfcd,t;
int *ilist,*jlist,*numneigh,**firstneigh;
ecoul = 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 double * _noalias const q = atom->q;
const int nlocal = atom->nlocal;
const double * _noalias const special_coul = force->special_coul;
const 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].x;
ytmp = x[i].y;
ztmp = x[i].z;
jlist = firstneigh[i];
jnum = numneigh[i];
fxtmp=fytmp=fztmp=0.0;
if (EFLAG) {
double e_self = -(e_shift/2.0 + alpha/MY_PIS) * qtmp*qtmp*qqrd2e;
ev_tally_thr(this,i,i,nlocal,0,0.0,e_self,0.0,0.0,0.0,0.0,thr);
}
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
factor_coul = special_coul[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;
if (rsq < cut_coulsq) {
r2inv = 1.0/rsq;
r = sqrt(rsq);
prefactor = qqrd2e*qtmp*q[j]/r;
erfcd = exp(-alpha*alpha*rsq);
t = 1.0 / (1.0 + EWALD_P*alpha*r);
erfcc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * erfcd;
forcecoul = prefactor * (erfcc/r + 2.0*alpha/MY_PIS * erfcd +
r*f_shift) * r;
if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;
fpair = forcecoul * 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) {
ecoul = prefactor * (erfcc - r*e_shift - rsq*f_shift);
if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
} else ecoul = 0.0;
if (EVFLAG) ev_tally_thr(this, i,j,nlocal,NEWTON_PAIR,
0.0,ecoul,fpair,delx,dely,delz,thr);
}
}
f[i].x += fxtmp;
f[i].y += fytmp;
f[i].z += fztmp;
}
}
/* ---------------------------------------------------------------------- */
double PairCoulDSFOMP::memory_usage()
{
double bytes = memory_usage_thr();
bytes += PairCoulDSF::memory_usage();
return bytes;
}
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