150 lines
4.1 KiB
C++
150 lines
4.1 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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https://www.lammps.org/, Sandia National Laboratories
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Steve Plimpton, sjplimp@sandia.gov
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Copyright (2003) Sandia Corporation. Under the terms of Contract
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DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
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certain rights in this software. This software is distributed under
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the GNU General Public License.
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See the README file in the top-level LAMMPS directory.
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------------------------------------------------------------------------- */
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#include "compute_dipole.h"
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#include "atom.h"
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#include "domain.h"
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#include "error.h"
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#include "update.h"
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#include <cmath>
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#include <cstring>
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using namespace LAMMPS_NS;
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enum { MASSCENTER, GEOMCENTER };
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/* ---------------------------------------------------------------------- */
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ComputeDipole::ComputeDipole(LAMMPS *lmp, int narg, char **arg) : Compute(lmp, narg, arg)
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{
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if ((narg < 3) || (narg > 4)) error->all(FLERR, "Illegal compute dipole command");
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scalar_flag = 1;
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vector_flag = 1;
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size_vector = 3;
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extscalar = 0;
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extvector = 0;
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vector = new double[size_vector];
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vector[0] = vector[1] = vector[2] = 0.0;
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usecenter = MASSCENTER;
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if (narg == 4) {
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if (utils::strmatch(arg[3], "^geom"))
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usecenter = GEOMCENTER;
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else if (strcmp(arg[3], "mass") == 0)
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usecenter = MASSCENTER;
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else
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error->all(FLERR, "Illegal compute dipole command");
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}
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}
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/* ---------------------------------------------------------------------- */
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ComputeDipole::~ComputeDipole()
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{
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delete[] vector;
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}
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/* ---------------------------------------------------------------------- */
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void ComputeDipole::compute_vector()
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{
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invoked_vector = update->ntimestep;
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const auto x = atom->x;
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const auto mask = atom->mask;
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const auto type = atom->type;
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const auto image = atom->image;
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const auto mass = atom->mass;
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const auto rmass = atom->rmass;
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const auto q = atom->q;
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const auto mu = atom->mu;
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const auto nlocal = atom->nlocal;
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double dipole[3] = {0.0, 0.0, 0.0};
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double comproc[3] = {0.0, 0.0, 0.0};
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double com[3] = {0.0, 0.0, 0.0};
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double masstotal = 0.0;
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double chrgtotal = 0.0;
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double massproc = 0.0;
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double chrgproc = 0.0;
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for (int i = 0; i < nlocal; ++i) {
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if (mask[i] & groupbit) {
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double unwrap[3];
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double massone = 1.0; // for usecenter == GEOMCENTER
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if (usecenter == MASSCENTER) {
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if (rmass)
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massone = rmass[i];
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else
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massone = mass[type[i]];
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}
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massproc += massone;
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if (atom->q_flag) chrgproc += q[i];
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domain->unmap(x[i], image[i], unwrap);
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comproc[0] += unwrap[0] * massone;
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comproc[1] += unwrap[1] * massone;
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comproc[2] += unwrap[2] * massone;
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}
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}
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MPI_Allreduce(&massproc, &masstotal, 1, MPI_DOUBLE, MPI_SUM, world);
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MPI_Allreduce(&chrgproc, &chrgtotal, 1, MPI_DOUBLE, MPI_SUM, world);
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MPI_Allreduce(comproc, com, 3, MPI_DOUBLE, MPI_SUM, world);
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if (masstotal > 0.0) {
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com[0] /= masstotal;
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com[1] /= masstotal;
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com[2] /= masstotal;
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}
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// compute dipole moment
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for (int i = 0; i < nlocal; i++) {
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if (mask[i] & groupbit) {
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double unwrap[3];
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domain->unmap(x[i], image[i], unwrap);
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if (atom->q_flag) {
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dipole[0] += q[i] * unwrap[0];
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dipole[1] += q[i] * unwrap[1];
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dipole[2] += q[i] * unwrap[2];
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}
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if (atom->mu_flag) {
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dipole[0] += mu[i][0];
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dipole[1] += mu[i][1];
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dipole[2] += mu[i][2];
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}
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}
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}
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MPI_Allreduce(dipole, vector, 3, MPI_DOUBLE, MPI_SUM, world);
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// correct for position dependence with a net charged group
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vector[0] -= chrgtotal * com[0];
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vector[1] -= chrgtotal * com[1];
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vector[2] -= chrgtotal * com[2];
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}
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/* ---------------------------------------------------------------------- */
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double ComputeDipole::compute_scalar()
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{
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if (invoked_vector != update->ntimestep) compute_vector();
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invoked_scalar = update->ntimestep;
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scalar = sqrt(vector[0] * vector[0] + vector[1] * vector[1] + vector[2] * vector[2]);
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return scalar;
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}
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