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lammps/src/fix_set_force.cpp
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fix_set_force.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 "stdlib.h"
#include "fix_set_force.h"
#include "atom.h"
#include "update.h"
#include "respa.h"
#include "error.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
FixSetForce::FixSetForce(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg != 6) error->all("Illegal fix setforce command");
vector_flag = 1;
size_vector = 3;
scalar_vector_freq = 1;
extvector = 1;
flagx = flagy = flagz = 1;
if (strcmp(arg[3],"NULL") == 0) flagx = 0;
else xvalue = atof(arg[3]);
if (strcmp(arg[4],"NULL") == 0) flagy = 0;
else yvalue = atof(arg[4]);
if (strcmp(arg[5],"NULL") == 0) flagz = 0;
else zvalue = atof(arg[5]);
force_flag = 0;
foriginal[0] = foriginal[1] = foriginal[2] = 0.0;
}
/* ---------------------------------------------------------------------- */
int FixSetForce::setmask()
{
int mask = 0;
mask |= POST_FORCE;
mask |= POST_FORCE_RESPA;
mask |= MIN_POST_FORCE;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixSetForce::init()
{
if (strcmp(update->integrate_style,"respa") == 0)
nlevels_respa = ((Respa *) update->integrate)->nlevels;
}
/* ---------------------------------------------------------------------- */
void FixSetForce::setup()
{
if (strcmp(update->integrate_style,"verlet") == 0)
post_force(1);
else
for (int ilevel = 0; ilevel < nlevels_respa; ilevel++) {
((Respa *) update->integrate)->copy_flevel_f(ilevel);
post_force_respa(1,ilevel,0);
((Respa *) update->integrate)->copy_f_flevel(ilevel);
}
}
/* ---------------------------------------------------------------------- */
void FixSetForce::min_setup()
{
post_force(1);
}
/* ---------------------------------------------------------------------- */
void FixSetForce::post_force(int vflag)
{
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
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];
if (flagx) f[i][0] = xvalue;
if (flagy) f[i][1] = yvalue;
if (flagz) f[i][2] = zvalue;
}
}
/* ---------------------------------------------------------------------- */
void FixSetForce::post_force_respa(int vflag, int ilevel, int iloop)
{
// set force to desired value on outermost level, 0.0 on other levels
if (ilevel == nlevels_respa-1) post_force(vflag);
else {
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
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];
if (flagx) f[i][0] = 0.0;
if (flagy) f[i][1] = 0.0;
if (flagz) f[i][2] = 0.0;
}
}
}
/* ---------------------------------------------------------------------- */
void FixSetForce::min_post_force(int vflag)
{
post_force(vflag);
}
/* ----------------------------------------------------------------------
return components of total force on fix group before reset
------------------------------------------------------------------------- */
double FixSetForce::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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