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lammps/src/ASPHERE/compute_erotate_asphere.cpp
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compute_erotate_asphere.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_asphere.h"
#include "math_extra.h"
#include "atom.h"
#include "update.h"
#include "force.h"
#include "memory.h"
#include "error.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
ComputeERotateAsphere::ComputeERotateAsphere(LAMMPS *lmp, int narg, char **arg) :
Compute(lmp, narg, arg)
{
if (narg != 3) error->all("Illegal compute erotate/asphere command");
if (!atom->angmom_flag || !atom->quat_flag)
error->all("Compute erotate/asphere requires atom attributes angmom, quat");
scalar_flag = 1;
extscalar = 1;
inertia =
memory->create_2d_double_array(atom->ntypes+1,3,"fix_temp_sphere:inertia");
}
/* ---------------------------------------------------------------------- */
ComputeERotateAsphere::~ComputeERotateAsphere()
{
memory->destroy_2d_double_array(inertia);
}
/* ---------------------------------------------------------------------- */
void ComputeERotateAsphere::init()
{
pfactor = 0.5 * force->mvv2e;
if (!atom->shape)
error->all("Compute erotate/asphere requires atom attribute shape");
calculate_inertia();
}
/* ---------------------------------------------------------------------- */
double ComputeERotateAsphere::compute_scalar()
{
invoked_scalar = update->ntimestep;
double **quat = atom->quat;
double **angmom = atom->angmom;
int *mask = atom->mask;
int *type = atom->type;
int nlocal = atom->nlocal;
int itype;
double wbody[3];
double rot[3][3];
double erotate = 0.0;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
itype = type[i];
// wbody = angular velocity in body frame
MathExtra::quat_to_mat(quat[i],rot);
MathExtra::transpose_times_column3(rot,angmom[i],wbody);
wbody[0] /= inertia[itype][0];
wbody[1] /= inertia[itype][1];
wbody[2] /= inertia[itype][2];
erotate += inertia[itype][0]*wbody[0]*wbody[0]+
inertia[itype][1]*wbody[1]*wbody[1]+
inertia[itype][2]*wbody[2]*wbody[2];
}
MPI_Allreduce(&erotate,&scalar,1,MPI_DOUBLE,MPI_SUM,world);
scalar *= pfactor;
return scalar;
}
/* ----------------------------------------------------------------------
principal moments of inertia for ellipsoids
------------------------------------------------------------------------- */
void ComputeERotateAsphere::calculate_inertia()
{
double *mass = atom->mass;
double **shape = atom->shape;
for (int i = 1; i <= atom->ntypes; i++) {
inertia[i][0] = mass[i] *
(shape[i][1]*shape[i][1]+shape[i][2]*shape[i][2]) / 5.0;
inertia[i][1] = mass[i] *
(shape[i][0]*shape[i][0]+shape[i][2]*shape[i][2]) / 5.0;
inertia[i][2] = mass[i] *
(shape[i][0]*shape[i][0]+shape[i][1]*shape[i][1]) / 5.0;
}
}
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