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lammps/src/USER-OMP/fix_nve_omp.cpp
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fix_nve_omp.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 "fix_nve_omp.h"
#include "atom.h"
#include "force.h"
using namespace LAMMPS_NS;
using namespace FixConst;
typedef struct { double x,y,z; } dbl3_t;
/* ---------------------------------------------------------------------- */
FixNVEOMP::FixNVEOMP(LAMMPS *lmp, int narg, char **arg) :
FixNVE(lmp, narg, arg) { }
/* ----------------------------------------------------------------------
allow for both per-type and per-atom mass
------------------------------------------------------------------------- */
void FixNVEOMP::initial_integrate(int vflag)
{
// update v and x of atoms in group
dbl3_t * _noalias const x = (dbl3_t *) atom->x[0];
dbl3_t * _noalias const v = (dbl3_t *) atom->v[0];
const dbl3_t * _noalias const f = (dbl3_t *) atom->f[0];
const int * const mask = atom->mask;
const int nlocal = (igroup == atom->firstgroup) ? atom->nfirst : atom->nlocal;
int i;
if (atom->rmass) {
const double * const rmass = atom->rmass;
#if defined (_OPENMP)
#pragma omp parallel for private(i) default(none) schedule(static)
#endif
for (i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
const double dtfm = dtf / rmass[i];
v[i].x += dtfm * f[i].x;
v[i].y += dtfm * f[i].y;
v[i].z += dtfm * f[i].z;
x[i].x += dtv * v[i].x;
x[i].y += dtv * v[i].y;
x[i].z += dtv * v[i].z;
}
} else {
const double * const mass = atom->mass;
const int * const type = atom->type;
#if defined (_OPENMP)
#pragma omp parallel for private(i) default(none) schedule(static)
#endif
for (i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
const double dtfm = dtf / mass[type[i]];
v[i].x += dtfm * f[i].x;
v[i].y += dtfm * f[i].y;
v[i].z += dtfm * f[i].z;
x[i].x += dtv * v[i].x;
x[i].y += dtv * v[i].y;
x[i].z += dtv * v[i].z;
}
}
}
/* ---------------------------------------------------------------------- */
void FixNVEOMP::final_integrate()
{
// update v of atoms in group
dbl3_t * _noalias const v = (dbl3_t *) atom->v[0];
const dbl3_t * _noalias const f = (dbl3_t *) atom->f[0];
const int * const mask = atom->mask;
const int nlocal = (igroup == atom->firstgroup) ? atom->nfirst : atom->nlocal;
int i;
if (atom->rmass) {
const double * const rmass = atom->rmass;
#if defined (_OPENMP)
#pragma omp parallel for private(i) default(none) schedule(static)
#endif
for (i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
const double dtfm = dtf / rmass[i];
v[i].x += dtfm * f[i].x;
v[i].y += dtfm * f[i].y;
v[i].z += dtfm * f[i].z;
}
} else {
const double * const mass = atom->mass;
const int * const type = atom->type;
#if defined (_OPENMP)
#pragma omp parallel for private(i) default(none) schedule(static)
#endif
for (i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
const double dtfm = dtf / mass[type[i]];
v[i].x += dtfm * f[i].x;
v[i].y += dtfm * f[i].y;
v[i].z += dtfm * f[i].z;
}
}
}
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