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npair_half_nsq_newtoff_omp.cpp
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Fri, Jul 5, 07:09

npair_half_nsq_newtoff_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
Copyright (2003) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the GNU General Public License.
See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */
#include "npair_half_nsq_newtoff_omp.h"
#include "npair_omp.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "atom.h"
#include "atom_vec.h"
#include "group.h"
#include "molecule.h"
#include "domain.h"
#include "my_page.h"
#include "error.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
NPairHalfNsqNewtoffOmp::NPairHalfNsqNewtoffOmp(LAMMPS *lmp) : NPair(lmp) {}
/* ----------------------------------------------------------------------
N^2 / 2 search for neighbor pairs with partial Newton's 3rd law
pair stored once if i,j are both owned and i < j
pair stored by me if j is ghost (also stored by proc owning j)
------------------------------------------------------------------------- */
void NPairHalfNsqNewtoffOmp::build(NeighList *list)
{
const int nlocal = (includegroup) ? atom->nfirst : atom->nlocal;
const int bitmask = (includegroup) ? group->bitmask[includegroup] : 0;
const int nall = atom->nlocal + atom->nghost;
const int molecular = atom->molecular;
const int moltemplate = (molecular == 2) ? 1 : 0;
NPAIR_OMP_INIT;
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(list)
#endif
NPAIR_OMP_SETUP(nlocal);
int i,j,n,itype,jtype,which,imol,iatom;
tagint tagprev;
double xtmp,ytmp,ztmp,delx,dely,delz,rsq;
int *neighptr;
double **x = atom->x;
int *type = atom->type;
int *mask = atom->mask;
tagint *tag = atom->tag;
tagint *molecule = atom->molecule;
tagint **special = atom->special;
int **nspecial = atom->nspecial;
int *molindex = atom->molindex;
int *molatom = atom->molatom;
Molecule **onemols = atom->avec->onemols;
int *ilist = list->ilist;
int *numneigh = list->numneigh;
int **firstneigh = list->firstneigh;
// each thread has its own page allocator
MyPage<int> &ipage = list->ipage[tid];
ipage.reset();
// loop over owned atoms, storing neighbors
for (i = ifrom; i < ito; i++) {
n = 0;
neighptr = ipage.vget();
itype = type[i];
xtmp = x[i][0];
ytmp = x[i][1];
ztmp = x[i][2];
if (moltemplate) {
imol = molindex[i];
iatom = molatom[i];
tagprev = tag[i] - iatom - 1;
}
// loop over remaining atoms, owned and ghost
// only store pair if i < j
for (j = i+1; j < nall; j++) {
if (includegroup && !(mask[j] & bitmask)) continue;
jtype = type[j];
if (exclude && exclusion(i,j,itype,jtype,mask,molecule)) continue;
delx = xtmp - x[j][0];
dely = ytmp - x[j][1];
delz = ztmp - x[j][2];
rsq = delx*delx + dely*dely + delz*delz;
if (rsq <= cutneighsq[itype][jtype]) {
if (molecular) {
if (!moltemplate)
which = find_special(special[i],nspecial[i],tag[j]);
else if (imol >=0)
which = find_special(onemols[imol]->special[iatom],
onemols[imol]->nspecial[iatom],
tag[j]-tagprev);
else which = 0;
if (which == 0) neighptr[n++] = j;
else if (domain->minimum_image_check(delx,dely,delz))
neighptr[n++] = j;
else if (which > 0) neighptr[n++] = j ^ (which << SBBITS);
} else neighptr[n++] = j;
}
}
ilist[i] = i;
firstneigh[i] = neighptr;
numneigh[i] = n;
ipage.vgot(n);
if (ipage.status())
error->one(FLERR,"Neighbor list overflow, boost neigh_modify one");
}
NPAIR_OMP_CLOSE;
list->inum = nlocal;
}

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