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lammps/src/compute_erotate_sphere_atom.cpp
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compute_erotate_sphere_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 <string.h>
#include "compute_erotate_sphere_atom.h"
#include "atom.h"
#include "update.h"
#include "modify.h"
#include "comm.h"
#include "force.h"
#include "memory.h"
#include "error.h"
using namespace LAMMPS_NS;
#define INERTIA 0.4 // moment of inertia prefactor for sphere
/* ---------------------------------------------------------------------- */
ComputeErotateSphereAtom::
ComputeErotateSphereAtom(LAMMPS *lmp, int narg, char **arg) :
Compute(lmp, narg, arg),
erot(NULL)
{
if (narg != 3)
error->all(FLERR,"Illegal compute erotate/sphere//atom command");
peratom_flag = 1;
size_peratom_cols = 0;
// error check
if (!atom->sphere_flag)
error->all(FLERR,"Compute erotate/sphere/atom requires atom style sphere");
nmax = 0;
}
/* ---------------------------------------------------------------------- */
ComputeErotateSphereAtom::~ComputeErotateSphereAtom()
{
memory->destroy(erot);
}
/* ---------------------------------------------------------------------- */
void ComputeErotateSphereAtom::init()
{
int count = 0;
for (int i = 0; i < modify->ncompute; i++)
if (strcmp(modify->compute[i]->style,"erotate/sphere/atom") == 0) count++;
if (count > 1 && comm->me == 0)
error->warning(FLERR,"More than one compute erotate/sphere/atom");
pfactor = 0.5 * force->mvv2e * INERTIA;
}
/* ---------------------------------------------------------------------- */
void ComputeErotateSphereAtom::compute_peratom()
{
invoked_peratom = update->ntimestep;
// grow erot array if necessary
if (atom->nmax > nmax) {
memory->destroy(erot);
nmax = atom->nmax;
memory->create(erot,nmax,"erotate/sphere/atom:erot");
vector_atom = erot;
}
// compute rotational kinetic energy for each atom in group
// point particles will have erot = 0.0, due to radius = 0.0
double **omega = atom->omega;
double *radius = atom->radius;
double *rmass = atom->rmass;
int *mask = atom->mask;
int nlocal = atom->nlocal;
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
erot[i] = (omega[i][0]*omega[i][0] + omega[i][1]*omega[i][1] +
omega[i][2]*omega[i][2]) * radius[i]*radius[i]*rmass[i];
erot[i] *= pfactor;
} else erot[i] = 0.0;
}
}
/* ----------------------------------------------------------------------
memory usage of local atom-based array
------------------------------------------------------------------------- */
double ComputeErotateSphereAtom::memory_usage()
{
double bytes = nmax * sizeof(double);
return bytes;
}
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