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pair_table_omp.cpp
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Thu, Nov 7, 11:05

pair_table_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_table_omp.h"
#include "atom.h"
#include "comm.h"
#include "error.h"
#include "force.h"
#include "neighbor.h"
#include "neigh_list.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
PairTableOMP::PairTableOMP(LAMMPS *lmp) :
PairTable(lmp), ThrOMP(lmp, THR_PAIR)
{
respa_enable = 0;
}
/* ---------------------------------------------------------------------- */
void PairTableOMP::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);
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);
}
reduce_thr(this, eflag, vflag, thr);
} // end of omp parallel region
}
template <int EVFLAG, int EFLAG, int NEWTON_PAIR>
void PairTableOMP::eval(int iifrom, int iito, ThrData * const thr)
{
int i,j,ii,jj,jnum,itype,jtype,itable;
double xtmp,ytmp,ztmp,delx,dely,delz,evdwl,fpair;
double rsq,factor_lj,fraction,value,a,b;
int *ilist,*jlist,*numneigh,**firstneigh;
Table *tb;
union_int_float_t rsq_lookup;
int tlm1 = tablength - 1;
evdwl = 0.0;
const double * const * const x = atom->x;
double * const * const f = thr->get_f();
const int * const type = atom->type;
const int nlocal = atom->nlocal;
const double * 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][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)];
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]) {
tb = &tables[tabindex[itype][jtype]];
if (rsq < tb->innersq)
error->one(FLERR,"Pair distance < table inner cutoff");
if (tabstyle == LOOKUP) {
itable = static_cast<int> ((rsq - tb->innersq) * tb->invdelta);
if (itable >= tlm1)
error->one(FLERR,"Pair distance > table outer cutoff");
fpair = factor_lj * tb->f[itable];
} else if (tabstyle == LINEAR) {
itable = static_cast<int> ((rsq - tb->innersq) * tb->invdelta);
if (itable >= tlm1)
error->one(FLERR,"Pair distance > table outer cutoff");
fraction = (rsq - tb->rsq[itable]) * tb->invdelta;
value = tb->f[itable] + fraction*tb->df[itable];
fpair = factor_lj * value;
} else if (tabstyle == SPLINE) {
itable = static_cast<int> ((rsq - tb->innersq) * tb->invdelta);
if (itable >= tlm1)
error->one(FLERR,"Pair distance > table outer cutoff");
b = (rsq - tb->rsq[itable]) * tb->invdelta;
a = 1.0 - b;
value = a * tb->f[itable] + b * tb->f[itable+1] +
((a*a*a-a)*tb->f2[itable] + (b*b*b-b)*tb->f2[itable+1]) *
tb->deltasq6;
fpair = factor_lj * value;
} else {
rsq_lookup.f = rsq;
itable = rsq_lookup.i & tb->nmask;
itable >>= tb->nshiftbits;
fraction = (rsq_lookup.f - tb->rsq[itable]) * tb->drsq[itable];
value = tb->f[itable] + fraction*tb->df[itable];
fpair = factor_lj * value;
}
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 (tabstyle == LOOKUP)
evdwl = tb->e[itable];
else if (tabstyle == LINEAR || tabstyle == BITMAP)
evdwl = tb->e[itable] + fraction*tb->de[itable];
else
evdwl = a * tb->e[itable] + b * tb->e[itable+1] +
((a*a*a-a)*tb->e2[itable] + (b*b*b-b)*tb->e2[itable+1]) *
tb->deltasq6;
evdwl *= factor_lj;
}
if (EVFLAG) ev_tally_thr(this,i,j,nlocal,NEWTON_PAIR,
evdwl,0.0,fpair,delx,dely,delz,thr);
}
}
f[i][0] += fxtmp;
f[i][1] += fytmp;
f[i][2] += fztmp;
}
}
/* ---------------------------------------------------------------------- */
double PairTableOMP::memory_usage()
{
double bytes = memory_usage_thr();
bytes += PairTable::memory_usage();
return bytes;
}

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