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fix_freeze.cpp
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Fri, Jun 7, 12:10

fix_freeze.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 "fix_freeze.h"
#include "atom.h"
#include "update.h"
#include "modify.h"
#include "comm.h"
#include "respa.h"
#include "error.h"
using namespace LAMMPS_NS;
using namespace FixConst;
/* ---------------------------------------------------------------------- */
FixFreeze::FixFreeze(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg != 3) error->all(FLERR,"Illegal fix freeze command");
if (!atom->torque_flag)
error->all(FLERR,"Fix freeze requires atom attribute torque");
vector_flag = 1;
size_vector = 3;
global_freq = 1;
extvector = 1;
force_flag = 0;
foriginal[0] = foriginal[1] = foriginal[2] = 0.0;
}
/* ---------------------------------------------------------------------- */
int FixFreeze::setmask()
{
int mask = 0;
mask |= POST_FORCE;
mask |= POST_FORCE_RESPA;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixFreeze::init()
{
// error if more than one freeze fix
// because accessed by pair style granular and fix gran/diag
int count = 0;
for (int i = 0; i < modify->nfix; i++)
if (strcmp(modify->fix[i]->style,"freeze") == 0) count++;
if (count > 1) error->all(FLERR,"More than one fix freeze");
}
/* ---------------------------------------------------------------------- */
void FixFreeze::setup(int vflag)
{
if (strstr(update->integrate_style,"verlet"))
post_force(vflag);
else {
int nlevels_respa = ((Respa *) update->integrate)->nlevels;
for (int ilevel = 0; ilevel < nlevels_respa; ilevel++) {
((Respa *) update->integrate)->copy_flevel_f(ilevel);
post_force_respa(vflag,ilevel,0);
((Respa *) update->integrate)->copy_f_flevel(ilevel);
}
}
}
/* ---------------------------------------------------------------------- */
void FixFreeze::post_force(int vflag)
{
double **f = atom->f;
double **torque = atom->torque;
int *mask = atom->mask;
int nlocal = atom->nlocal;
if (igroup == atom->firstgroup) nlocal = atom->nfirst;
foriginal[0] = foriginal[1] = foriginal[2] = 0.0;
force_flag = 0;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
foriginal[0] += f[i][0];
foriginal[1] += f[i][1];
foriginal[2] += f[i][2];
f[i][0] = 0.0;
f[i][1] = 0.0;
f[i][2] = 0.0;
torque[i][0] = 0.0;
torque[i][1] = 0.0;
torque[i][2] = 0.0;
}
}
/* ---------------------------------------------------------------------- */
void FixFreeze::post_force_respa(int vflag, int ilevel, int iloop)
{
post_force(vflag);
}
/* ----------------------------------------------------------------------
return components of total force on fix group before force was changed
------------------------------------------------------------------------- */
double FixFreeze::compute_vector(int n)
{
// only sum across procs one time
if (force_flag == 0) {
MPI_Allreduce(foriginal,foriginal_all,3,MPI_DOUBLE,MPI_SUM,world);
force_flag = 1;
}
return foriginal_all[n];
}

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