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lammps/src/compute_cluster_atom.cpp
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compute_cluster_atom.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 "math.h"
#include "string.h"
#include "stdlib.h"
#include "compute_cluster_atom.h"
#include "atom.h"
#include "update.h"
#include "modify.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "force.h"
#include "pair.h"
#include "comm.h"
#include "memory.h"
#include "error.h"
using namespace LAMMPS_NS;
#define MIN(A,B) ((A) < (B)) ? (A) : (B)
#define MAX(A,B) ((A) > (B)) ? (A) : (B)
/* ---------------------------------------------------------------------- */
ComputeClusterAtom::ComputeClusterAtom(LAMMPS *lmp, int narg, char **arg) :
Compute(lmp, narg, arg)
{
if (narg != 4) error->all("Illegal compute cluster/atom command");
double cutoff = atof(arg[3]);
cutsq = cutoff*cutoff;
peratom_flag = 1;
size_peratom_cols = 0;
comm_forward = 1;
nmax = 0;
clusterID = NULL;
}
/* ---------------------------------------------------------------------- */
ComputeClusterAtom::~ComputeClusterAtom()
{
memory->destroy(clusterID);
}
/* ---------------------------------------------------------------------- */
void ComputeClusterAtom::init()
{
if (atom->tag_enable == 0)
error->all("Cannot use compute cluster/atom unless atoms have IDs");
if (force->pair == NULL)
error->all("Compute cluster/atom requires a pair style be defined");
if (sqrt(cutsq) > force->pair->cutforce)
error->all("Compute cluster/atom cutoff is longer than pairwise cutoff");
// need an occasional full neighbor list
// full required so that pair of atoms on 2 procs both set their clusterID
int irequest = neighbor->request((void *) this);
neighbor->requests[irequest]->pair = 0;
neighbor->requests[irequest]->compute = 1;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->full = 1;
neighbor->requests[irequest]->occasional = 1;
int count = 0;
for (int i = 0; i < modify->ncompute; i++)
if (strcmp(modify->compute[i]->style,"cluster/atom") == 0) count++;
if (count > 1 && comm->me == 0)
error->warning("More than one compute cluster/atom");
}
/* ---------------------------------------------------------------------- */
void ComputeClusterAtom::init_list(int id, NeighList *ptr)
{
list = ptr;
}
/* ---------------------------------------------------------------------- */
void ComputeClusterAtom::compute_peratom()
{
int i,j,ii,jj,inum,jnum,n;
double xtmp,ytmp,ztmp,delx,dely,delz,rsq;
int *ilist,*jlist,*numneigh,**firstneigh;
invoked_peratom = update->ntimestep;
// grow clusterID array if necessary
if (atom->nlocal > nmax) {
memory->destroy(clusterID);
nmax = atom->nmax;
memory->create(clusterID,nmax,"cluster/atom:clusterID");
vector_atom = clusterID;
}
// invoke full neighbor list (will copy or build if necessary)
neighbor->build_one(list->index);
inum = list->inum;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
// every atom starts in its own cluster, with clusterID = atomID
int *tag = atom->tag;
int *mask = atom->mask;
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
if (mask[i] & groupbit) clusterID[i] = tag[i];
else clusterID[i] = 0;
}
// loop until no more changes on any proc:
// acquire clusterIDs of ghost atoms
// loop over my atoms, checking distance to neighbors
// if both atoms are in cluster, assign lowest clusterID to both
// iterate until no changes in my atoms
// then check if any proc made changes
double **x = atom->x;
int nall = atom->nlocal + atom->nghost;
int change,done,anychange;
while (1) {
comm->forward_comm_compute(this);
change = 0;
while (1) {
done = 1;
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
if (!(mask[i] & groupbit)) continue;
xtmp = x[i][0];
ytmp = x[i][1];
ztmp = x[i][2];
jlist = firstneigh[i];
jnum = numneigh[i];
n = 0;
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
if (j >= nall) j %= nall;
if (!(mask[j] & groupbit)) continue;
if (clusterID[i] == clusterID[j]) 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 < cutsq) {
clusterID[i] = clusterID[j] = MIN(clusterID[i],clusterID[j]);
done = 0;
}
}
}
if (!done) change = 1;
if (done) break;
}
// stop if all procs are done
MPI_Allreduce(&change,&anychange,1,MPI_INT,MPI_MAX,world);
if (!anychange) break;
}
}
/* ---------------------------------------------------------------------- */
int ComputeClusterAtom::pack_comm(int n, int *list, double *buf,
int pbc_flag, int *pbc)
{
int i,j,m;
m = 0;
for (i = 0; i < n; i++) {
j = list[i];
buf[m++] = clusterID[j];
}
return 1;
}
/* ---------------------------------------------------------------------- */
void ComputeClusterAtom::unpack_comm(int n, int first, double *buf)
{
int i,m,last;
m = 0;
last = first + n;
for (i = first; i < last; i++) clusterID[i] = buf[m++];
}
/* ----------------------------------------------------------------------
memory usage of local atom-based array
------------------------------------------------------------------------- */
double ComputeClusterAtom::memory_usage()
{
double bytes = nmax * sizeof(double);
return bytes;
}
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