Files
lammps/src/npair_nsq.cpp

233 lines
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C++

/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
https://www.lammps.org/, Sandia National Laboratories
LAMMPS development team: developers@lammps.org
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_nsq.h"
#include "atom.h"
#include "atom_vec.h"
#include "domain.h"
#include "error.h"
#include "force.h"
#include "group.h"
#include "molecule.h"
#include "my_page.h"
#include "neigh_list.h"
#include "neighbor.h"
#include <cmath>
using namespace LAMMPS_NS;
using namespace NeighConst;
/* ---------------------------------------------------------------------- */
template<int HALF, int NEWTON, int TRI, int SIZE>
NPairNsq<HALF, NEWTON, TRI, SIZE>::NPairNsq(LAMMPS *lmp) : NPair(lmp) {}
/* ----------------------------------------------------------------------
Full:
N^2 search for all neighbors
every neighbor pair appears in list of both atoms i and j
Half + Newtoff:
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)
Half + Newton:
N^2 / 2 search for neighbor pairs with full Newton's 3rd law
every pair stored exactly once by some processor
decision on ghost atoms based on itag, jtag tests
Half + Newton + Tri:
use itag/jtap comparision to eliminate half the interactions
for triclinic, must use delta to eliminate half the I/J interactions
cannot use I/J exact coord comparision as for orthog
b/c transforming orthog -> lambda -> orthog for ghost atoms
with an added PBC offset can shift all 3 coords by epsilon
------------------------------------------------------------------------- */
template<int HALF, int NEWTON, int TRI, int SIZE>
void NPairNsq<HALF, NEWTON, TRI, SIZE>::build(NeighList *list)
{
int i, j, jh, jstart, n, itype, jtype, which, bitmask, imol, iatom, moltemplate;
tagint itag, jtag, tagprev;
double xtmp, ytmp, ztmp, delx, dely, delz, rsq, radsum, cut, cutsq;
int *neighptr;
const double delta = 0.01 * force->angstrom;
double **x = atom->x;
double *radius = atom->radius;
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 nlocal = atom->nlocal;
int nall = nlocal + atom->nghost;
if (includegroup) {
nlocal = atom->nfirst;
bitmask = group->bitmask[includegroup];
}
int *molindex = atom->molindex;
int *molatom = atom->molatom;
Molecule **onemols = atom->avec->onemols;
if (molecular == Atom::TEMPLATE)
moltemplate = 1;
else
moltemplate = 0;
int history = list->history;
int mask_history = 1 << HISTBITS;
int *ilist = list->ilist;
int *numneigh = list->numneigh;
int **firstneigh = list->firstneigh;
MyPage<int> *ipage = list->ipage;
int inum = 0;
ipage->reset();
for (i = 0; i < nlocal; i++) {
n = 0;
neighptr = ipage->vget();
itag = tag[i];
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;
}
// Full: loop over all atoms, owned and ghost, skip i = j
// Half: loop over remaining atoms, owned and ghost
// Newtoff: only store pair if i < j
// Newton: itag = jtag is possible for long cutoffs that include images of self
if (!HALF) jstart = 0;
else jstart = i + 1;
for (j = jstart; j < nall; j++) {
if (includegroup && !(mask[j] & bitmask)) continue;
if (!HALF) {
// Full neighbor list
if (i == j) continue;
} else if (NEWTON) {
// Half neighbor list, newton on
if (j >= nlocal) {
jtag = tag[j];
if (itag > jtag) {
if ((itag + jtag) % 2 == 0) continue;
} else if (itag < jtag) {
if ((itag + jtag) % 2 == 1) continue;
} else if (TRI) {
if (fabs(x[j][2] - ztmp) > delta) {
if (x[j][2] < ztmp) continue;
} else if (fabs(x[j][1] - ytmp) > delta) {
if (x[j][1] < ytmp) continue;
} else {
if (x[j][0] < xtmp) continue;
}
} else {
if (x[j][2] < ztmp) continue;
if (x[j][2] == ztmp) {
if (x[j][1] < ytmp) continue;
if (x[j][1] == ytmp && x[j][0] < xtmp) 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 (SIZE) {
radsum = radius[i] + radius[j];
cut = radsum + skin;
cutsq = cut * cut;
if (rsq <= cutsq) {
jh = j;
if (history && rsq < radsum * radsum) jh = jh ^ mask_history;
if (molecular != Atom::ATOMIC) {
if (!moltemplate)
which = find_special(special[i], nspecial[i], tag[j]);
else if ((imol >= 0) && onemols[imol]->special)
which = find_special(onemols[imol]->special[iatom], onemols[imol]->nspecial[iatom],
tag[j] - tagprev);
else
which = 0;
if (which == 0)
neighptr[n++] = jh;
else if (domain->minimum_image_check(delx, dely, delz))
neighptr[n++] = jh;
else if (which > 0)
neighptr[n++] = jh ^ (which << SBBITS);
} else
neighptr[n++] = jh;
}
} else {
if (rsq <= cutneighsq[itype][jtype]) {
if (molecular != Atom::ATOMIC) {
if (!moltemplate)
which = find_special(special[i], nspecial[i], tag[j]);
else if ((imol >= 0) && onemols[imol]->special)
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[inum++] = i;
firstneigh[i] = neighptr;
numneigh[i] = n;
ipage->vgot(n);
if (ipage->status()) error->one(FLERR, Error::NOLASTLINE, "Neighbor list overflow, boost neigh_modify one" + utils::errorurl(36));
}
list->inum = inum;
if (!HALF) list->gnum = 0;
}
namespace LAMMPS_NS {
template class NPairNsq<0,1,0,0>;
template class NPairNsq<1,0,0,0>;
template class NPairNsq<1,1,0,0>;
template class NPairNsq<1,1,1,0>;
template class NPairNsq<0,1,0,1>;
template class NPairNsq<1,0,0,1>;
template class NPairNsq<1,1,0,1>;
template class NPairNsq<1,1,1,1>;
}