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fix_qeq_comb_omp.cpp
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Sat, Nov 9, 15:14

fix_qeq_comb_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.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing author: Axel Kohlmeyer (Temple U)
------------------------------------------------------------------------- */
#include <mpi.h>
#include <math.h>
#include "fix_qeq_comb_omp.h"
#include "fix_omp.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "group.h"
#include "memory.h"
#include "modify.h"
#include "error.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "respa.h"
#include "update.h"
#include "pair_comb_omp.h"
#include <string.h>
using namespace LAMMPS_NS;
using namespace FixConst;
/* ---------------------------------------------------------------------- */
FixQEQCombOMP::FixQEQCombOMP(LAMMPS *lmp, int narg, char **arg) :
FixQEQComb(lmp, narg, arg)
{
if (narg < 5) error->all(FLERR,"Illegal fix qeq/comb/omp command");
}
/* ---------------------------------------------------------------------- */
void FixQEQCombOMP::init()
{
if (!atom->q_flag)
error->all(FLERR,"Fix qeq/comb/omp requires atom attribute q");
if (NULL != force->pair_match("comb3",0))
error->all(FLERR,"No support for comb3 currently available in USER-OMP");
comb = (PairComb *) force->pair_match("comb/omp",1);
if (comb == NULL)
comb = (PairComb *) force->pair_match("comb",1);
if (comb == NULL)
error->all(FLERR,"Must use pair_style comb or "
"comb/omp with fix qeq/comb/omp");
if (strstr(update->integrate_style,"respa")) {
ilevel_respa = ((Respa *) update->integrate)->nlevels-1;
if (respa_level >= 0) ilevel_respa = MIN(respa_level,ilevel_respa);
}
ngroup = group->count(igroup);
if (ngroup == 0) error->all(FLERR,"Fix qeq/comb group has no atoms");
// determine status of neighbor flag of the omp package command
int ifix = modify->find_fix("package_omp");
int use_omp = 0;
if (ifix >=0) {
FixOMP * fix = static_cast<FixOMP *>(lmp->modify->fix[ifix]);
if (fix->get_neighbor()) use_omp = 1;
}
int irequest = neighbor->request(this,instance_me);
neighbor->requests[irequest]->omp = use_omp;
}
/* ---------------------------------------------------------------------- */
void FixQEQCombOMP::post_force(int vflag)
{
int i,ii,iloop,loopmax,inum,*ilist;
double heatpq,qmass,dtq,dtq2;
double enegchkall,enegmaxall;
if (update->ntimestep % nevery) return;
// reallocate work arrays if necessary
// qf = charge force
// q1 = charge displacement
// q2 = tmp storage of charge force for next iteration
if (atom->nmax > nmax) {
memory->destroy(qf);
memory->destroy(q1);
memory->destroy(q2);
nmax = atom->nmax;
memory->create(qf,nmax,"qeq:qf");
memory->create(q1,nmax,"qeq:q1");
memory->create(q2,nmax,"qeq:q2");
vector_atom = qf;
}
// more loops for first-time charge equilibrium
iloop = 0;
if (firstflag) loopmax = 500;
else loopmax = 200;
// charge-equilibration loop
if (me == 0 && fp)
fprintf(fp,"Charge equilibration on step " BIGINT_FORMAT "\n",
update->ntimestep);
heatpq = 0.05;
qmass = 0.016;
dtq = 0.01;
dtq2 = 0.5*dtq*dtq/qmass;
double enegchk = 0.0;
double enegtot = 0.0;
double enegmax = 0.0;
double *q = atom->q;
int *mask = atom->mask;
inum = comb->list->inum;
ilist = comb->list->ilist;
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
q1[i] = q2[i] = qf[i] = 0.0;
}
for (iloop = 0; iloop < loopmax; iloop ++ ) {
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
if (mask[i] & groupbit) {
q1[i] += qf[i]*dtq2 - heatpq*q1[i];
q[i] += q1[i];
}
}
comm->forward_comm_fix(this);
if(comb) enegtot = comb->yasu_char(qf,igroup);
enegtot /= ngroup;
enegchk = enegmax = 0.0;
for (ii = 0; ii < inum ; ii++) {
i = ilist[ii];
if (mask[i] & groupbit) {
q2[i] = enegtot-qf[i];
enegmax = MAX(enegmax,fabs(q2[i]));
enegchk += fabs(q2[i]);
qf[i] = q2[i];
}
}
MPI_Allreduce(&enegchk,&enegchkall,1,MPI_DOUBLE,MPI_SUM,world);
enegchk = enegchkall/ngroup;
MPI_Allreduce(&enegmax,&enegmaxall,1,MPI_DOUBLE,MPI_MAX,world);
enegmax = enegmaxall;
if (enegchk <= precision && enegmax <= 100.0*precision) break;
if (me == 0 && fp)
fprintf(fp," iteration: %d, enegtot %.6g, "
"enegmax %.6g, fq deviation: %.6g\n",
iloop,enegtot,enegmax,enegchk);
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
if (mask[i] & groupbit)
q1[i] += qf[i]*dtq2 - heatpq*q1[i];
}
}
if (me == 0 && fp) {
if (iloop == loopmax)
fprintf(fp,"Charges did not converge in %d iterations\n",iloop);
else
fprintf(fp,"Charges converged in %d iterations to %.10f tolerance\n",
iloop,enegchk);
}
}

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