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compute_erotate_sphere.cpp
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Tue, Jul 2, 05:08

compute_erotate_sphere.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 "mpi.h"
#include "compute_erotate_sphere.h"
#include "atom.h"
#include "atom_vec.h"
#include "update.h"
#include "force.h"
#include "domain.h"
#include "group.h"
#include "error.h"
using namespace LAMMPS_NS;
#define INERTIA 0.4 // moment of inertia prefactor for sphere
/* ---------------------------------------------------------------------- */
ComputeERotateSphere::ComputeERotateSphere(LAMMPS *lmp, int narg, char **arg) :
Compute(lmp, narg, arg)
{
if (narg != 3) error->all(FLERR,"Illegal compute erotate/sphere command");
scalar_flag = 1;
extscalar = 1;
// error check
if (!atom->sphere_flag)
error->all(FLERR,"Compute erotate/sphere requires atom style sphere");
}
/* ---------------------------------------------------------------------- */
void ComputeERotateSphere::init()
{
pfactor = 0.5 * force->mvv2e * INERTIA;
}
/* ---------------------------------------------------------------------- */
double ComputeERotateSphere::compute_scalar()
{
invoked_scalar = update->ntimestep;
double **omega = atom->omega;
double *radius = atom->radius;
double *rmass = atom->rmass;
int *mask = atom->mask;
int nlocal = atom->nlocal;
// sum rotational energy for each particle
// point particles will not contribute, due to radius = 0.0
double erotate = 0.0;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit)
erotate += (omega[i][0]*omega[i][0] + omega[i][1]*omega[i][1] +
omega[i][2]*omega[i][2]) * radius[i]*radius[i]*rmass[i];
MPI_Allreduce(&erotate,&scalar,1,MPI_DOUBLE,MPI_SUM,world);
scalar *= pfactor;
return scalar;
}

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