mirror of https://github.com/lammps/lammps.git
88 lines
2.5 KiB
C++
88 lines
2.5 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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http://lammps.sandia.gov, 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 "mpi.h"
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#include "compute_rotate_dipole.h"
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#include "atom.h"
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#include "force.h"
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#include "group.h"
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#include "error.h"
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using namespace LAMMPS_NS;
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#define INERTIA3D 0.4 // moments of inertia for sphere and disk
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#define INERTIA2D 0.5
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/* ---------------------------------------------------------------------- */
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ComputeRotateDipole::ComputeRotateDipole(LAMMPS *lmp, int narg, char **arg) :
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Compute(lmp, narg, arg)
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{
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if (narg != 3) error->all("Illegal compute rotate/dipole command");
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if (atom->dipole == NULL || !atom->omega_flag)
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error->all("Compute rotate/dipole requires atom attributes dipole, omega");
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scalar_flag = 1;
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extensive = 1;
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inertia = NULL;
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}
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/* ---------------------------------------------------------------------- */
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ComputeRotateDipole::~ComputeRotateDipole()
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{
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delete [] inertia;
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}
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/* ---------------------------------------------------------------------- */
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void ComputeRotateDipole::init()
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{
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delete [] inertia;
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inertia = new double[atom->ntypes+1];
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double *mass = atom->mass;
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double **shape = atom->shape;
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if (force->dimension == 3)
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for (int i = 1; i <= atom->ntypes; i++)
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inertia[i] = INERTIA3D * mass[i] * 0.25*shape[i][0]*shape[i][0];
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else
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for (int i = 1; i <= atom->ntypes; i++)
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inertia[i] = INERTIA2D * mass[i] * 0.25*shape[i][0]*shape[i][0];
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}
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/* ---------------------------------------------------------------------- */
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double ComputeRotateDipole::compute_scalar()
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{
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double *dipole = atom->dipole;
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double **omega = atom->omega;
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int *type = atom->type;
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int *mask = atom->mask;
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int nlocal = atom->nlocal;
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double erot = 0.0;
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit && dipole[type[i]] > 0.0)
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erot += inertia[type[i]] *
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(omega[i][0]*omega[i][0] + omega[i][1]*omega[i][1] +
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omega[i][2]*omega[i][2]);
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MPI_Allreduce(&erot,&scalar,1,MPI_DOUBLE,MPI_SUM,world);
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scalar *= 0.5;
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return scalar;
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}
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