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fix_aveforce.cpp
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Sat, Sep 14, 12:30

fix_aveforce.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 "mpi.h"
#include "string.h"
#include "stdlib.h"
#include "fix_aveforce.h"
#include "atom.h"
#include "update.h"
#include "domain.h"
#include "region.h"
#include "respa.h"
#include "error.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
FixAveForce::FixAveForce(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg < 6) error->all("Illegal fix aveforce command");
vector_flag = 1;
size_vector = 3;
global_freq = 1;
extvector = 1;
xflag = yflag = zflag = 1;
if (strcmp(arg[3],"NULL") == 0) xflag = 0;
else xvalue = atof(arg[3]);
if (strcmp(arg[4],"NULL") == 0) yflag = 0;
else yvalue = atof(arg[4]);
if (strcmp(arg[5],"NULL") == 0) zflag = 0;
else zvalue = atof(arg[5]);
// optional args
iregion = -1;
int iarg = 6;
while (iarg < narg) {
if (strcmp(arg[iarg],"region") == 0) {
if (iarg+2 > narg) error->all("Illegal fix aveforce command");
iregion = domain->find_region(arg[iarg+1]);
if (iregion == -1) error->all("Fix aveforce region ID does not exist");
iarg += 2;
} else error->all("Illegal fix aveforce command");
}
foriginal_all[0] = foriginal_all[1] =
foriginal_all[2] = foriginal_all[3] = 0.0;
}
/* ---------------------------------------------------------------------- */
int FixAveForce::setmask()
{
int mask = 0;
mask |= POST_FORCE;
mask |= POST_FORCE_RESPA;
mask |= MIN_POST_FORCE;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixAveForce::init()
{
if (strcmp(update->integrate_style,"respa") == 0)
nlevels_respa = ((Respa *) update->integrate)->nlevels;
}
/* ---------------------------------------------------------------------- */
void FixAveForce::setup(int vflag)
{
if (strcmp(update->integrate_style,"verlet") == 0)
post_force(vflag);
else
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 FixAveForce::min_setup(int vflag)
{
post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixAveForce::post_force(int vflag)
{
// sum forces on participating atoms
double **x = atom->x;
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
double foriginal[4];
foriginal[0] = foriginal[1] = foriginal[2] = foriginal[3] = 0.0;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
if (iregion >= 0 &&
!domain->regions[iregion]->match(x[i][0],x[i][1],x[i][2]))
continue;
foriginal[0] += f[i][0];
foriginal[1] += f[i][1];
foriginal[2] += f[i][2];
foriginal[3] += 1.0;
}
// average the force on participating atoms
// add in requested amount
MPI_Allreduce(foriginal,foriginal_all,4,MPI_DOUBLE,MPI_SUM,world);
int ncount = static_cast<int> (foriginal_all[3]);
if (ncount == 0) return;
double fave[3];
fave[0] = foriginal_all[0]/ncount + xvalue;
fave[1] = foriginal_all[1]/ncount + yvalue;
fave[2] = foriginal_all[2]/ncount + zvalue;
// set force of all participating atoms to same value
// only for active dimensions
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
if (iregion >= 0 &&
!domain->regions[iregion]->match(x[i][0],x[i][1],x[i][2]))
continue;
if (xflag) f[i][0] = fave[0];
if (yflag) f[i][1] = fave[1];
if (zflag) f[i][2] = fave[2];
}
}
/* ---------------------------------------------------------------------- */
void FixAveForce::post_force_respa(int vflag, int ilevel, int iloop)
{
// ave + extra force on outermost level
// just ave on inner levels
if (ilevel == nlevels_respa-1) post_force(vflag);
else {
double **x = atom->x;
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
double foriginal[4];
foriginal[0] = foriginal[1] = foriginal[2] = foriginal[3] = 0.0;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
if (iregion >= 0 &&
!domain->regions[iregion]->match(x[i][0],x[i][1],x[i][2]))
continue;
foriginal[0] += f[i][0];
foriginal[1] += f[i][1];
foriginal[2] += f[i][2];
foriginal[3] += 1.0;
}
MPI_Allreduce(foriginal,foriginal_all,4,MPI_DOUBLE,MPI_SUM,world);
int ncount = static_cast<int> (foriginal_all[3]);
if (ncount == 0) return;
double fave[3];
fave[0] = foriginal_all[0]/ncount;
fave[1] = foriginal_all[1]/ncount;
fave[2] = foriginal_all[2]/ncount;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
if (iregion >= 0 &&
!domain->regions[iregion]->match(x[i][0],x[i][1],x[i][2]))
continue;
if (xflag) f[i][0] = fave[0];
if (yflag) f[i][1] = fave[1];
if (zflag) f[i][2] = fave[2];
}
}
}
/* ---------------------------------------------------------------------- */
void FixAveForce::min_post_force(int vflag)
{
post_force(vflag);
}
/* ----------------------------------------------------------------------
return components of total force on fix group before force was changed
------------------------------------------------------------------------- */
double FixAveForce::compute_vector(int n)
{
return foriginal_all[n];
}

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