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lammps/src/fix_nve_noforce.cpp
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fix_nve_noforce.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 <stdio.h>
#include <string.h>
#include "fix_nve_noforce.h"
#include "atom.h"
#include "update.h"
#include "respa.h"
#include "error.h"
using namespace LAMMPS_NS;
using namespace FixConst;
/* ---------------------------------------------------------------------- */
FixNVENoforce::FixNVENoforce(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg != 3) error->all(FLERR,"Illegal fix nve/noforce command");
time_integrate = 1;
}
/* ---------------------------------------------------------------------- */
int FixNVENoforce::setmask()
{
int mask = 0;
mask |= INITIAL_INTEGRATE;
mask |= INITIAL_INTEGRATE_RESPA;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixNVENoforce::init()
{
dtv = update->dt;
if (strstr(update->integrate_style,"respa"))
step_respa = ((Respa *) update->integrate)->step;
}
/* ---------------------------------------------------------------------- */
void FixNVENoforce::initial_integrate(int vflag)
{
double **x = atom->x;
double **v = atom->v;
int *mask = atom->mask;
int nlocal = atom->nlocal;
if (igroup == atom->firstgroup) nlocal = atom->nfirst;
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
x[i][0] += dtv * v[i][0];
x[i][1] += dtv * v[i][1];
x[i][2] += dtv * v[i][2];
}
}
}
/* ---------------------------------------------------------------------- */
void FixNVENoforce::initial_integrate_respa(int vflag, int ilevel, int flag)
{
if (flag) return; // only used by NPT,NPH
dtv = step_respa[ilevel];
if (ilevel == 0) initial_integrate(vflag);
}
/* ---------------------------------------------------------------------- */
void FixNVENoforce::reset_dt()
{
dtv = update->dt;
}
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