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compute_temp_dipole.cpp
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Sun, Feb 23, 11:43

compute_temp_dipole.cpp
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
www.cs.sandia.gov/~sjplimp/lammps.html
Steve Plimpton, sjplimp@sandia.gov, Sandia National Laboratories
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_temp_dipole.h"
#include "atom.h"
#include "force.h"
#include "group.h"
#include "modify.h"
#include "fix.h"
#include "error.h"
using namespace LAMMPS_NS;
// moment of inertia for a sphere
#define INERTIA 0.4
/* ---------------------------------------------------------------------- */
ComputeTempDipole::ComputeTempDipole(LAMMPS *lmp, int narg, char **arg) :
Compute(lmp, narg, arg)
{
if (narg != 3) error->all("Illegal compute temp/dipole command");
if (atom->omega == NULL || atom->shape == NULL)
error->all("Compute temp/dipole requires atom attributes omega, shape");
scalar_flag = vector_flag = 1;
size_vector = 6;
extensive = 0;
tempflag = 1;
vector = new double[6];
inertia = new double[atom->ntypes + 1];
}
/* ---------------------------------------------------------------------- */
ComputeTempDipole::~ComputeTempDipole()
{
delete [] vector;
delete [] inertia;
}
/* ---------------------------------------------------------------------- */
void ComputeTempDipole::init()
{
fix_dof = 0;
for (int i = 0; i < modify->nfix; i++)
fix_dof += modify->fix[i]->dof(igroup);
recount();
// moment of inertia for each particle type
double *mass = atom->mass;
double **shape = atom->shape;
for (int i = 1; i <= atom->ntypes; i++)
inertia[i] = INERTIA * mass[i] * 0.25*shape[i][0]*shape[i][0];
}
/* ---------------------------------------------------------------------- */
void ComputeTempDipole::recount()
{
double natoms = group->count(igroup);
dof = 2.0 * force->dimension * natoms;
dof -= extra_dof + fix_dof;
if (dof > 0) tfactor = force->mvv2e / (dof * force->boltz);
else tfactor = 0.0;
}
/* ---------------------------------------------------------------------- */
double ComputeTempDipole::compute_scalar()
{
double **v = atom->v;
double *mass = atom->mass;
double **omega = atom->omega;
int *type = atom->type;
int *mask = atom->mask;
int nlocal = atom->nlocal;
// rotational and translational kinetic energy
double t = 0.0;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit)
t += (v[i][0]*v[i][0] + v[i][1]*v[i][1] + v[i][2]*v[i][2]) *
mass[type[i]]
+ (omega[i][0] * omega[i][0] + omega[i][1] * omega[i][1] +
omega[i][2] * omega[i][2]) * inertia[type[i]];
MPI_Allreduce(&t,&scalar,1,MPI_DOUBLE,MPI_SUM,world);
if (dynamic) recount();
scalar *= tfactor;
return scalar;
}
/* ---------------------------------------------------------------------- */
void ComputeTempDipole::compute_vector()
{
int i;
double **v = atom->v;
double *mass = atom->mass;
double **omega = atom->omega;
int *type = atom->type;
int *mask = atom->mask;
int nlocal = atom->nlocal;
double rmass,imass,t[6];
for (i = 0; i < 6; i++) t[i] = 0.0;
// rotational and translational kinetic energy
for (i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
rmass = mass[type[i]];
imass = inertia[type[i]];
t[0] += rmass*v[i][0]*v[i][0] + imass*omega[i][0]*omega[i][0];
t[1] += rmass*v[i][1]*v[i][1] + imass*omega[i][1]*omega[i][1];
t[2] += rmass*v[i][2]*v[i][2] + imass*omega[i][2]*omega[i][2];
t[3] += rmass*v[i][0]*v[i][1] + imass*omega[i][0]*omega[i][1];
t[4] += rmass*v[i][0]*v[i][2] + imass*omega[i][0]*omega[i][2];
t[5] += rmass*v[i][1]*v[i][2] + imass*omega[i][1]*omega[i][2];
}
MPI_Allreduce(&t,&vector,6,MPI_DOUBLE,MPI_SUM,world);
for (i = 0; i < 6; i++) vector[i] *= force->mvv2e;
}

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