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fix_volume_rescale.cpp
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Tue, Nov 19, 06:31

fix_volume_rescale.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 "math.h"
#include "fix_volume_rescale.h"
#include "update.h"
#include "force.h"
#include "modify.h"
#include "kspace.h"
#include "domain.h"
#include "atom.h"
#include "error.h"
using namespace LAMMPS_NS;
/* ---------------------------------------------------------------------- */
FixVolRescale::FixVolRescale(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg < 7) error->all("Illegal fix volume/rescale command");
box_change = 1;
nevery = atoi(arg[3]);
if (nevery <= 0) error->all("Illegal fix volume/rescale command");
xflag = yflag = zflag = 0;
int iarg = 4;
while (iarg < narg) {
if (strcmp(arg[iarg],"x") == 0) {
if (iarg+3 > narg) error->all("Illegal fix volume/rescale command");
if (domain->xperiodic == 0)
error->all("Cannot fix volume/rescale on a non-periodic boundary");
xflag = 1;
xlo_stop = atof(arg[iarg+1]);
xhi_stop = atof(arg[iarg+2]);
iarg += 3;
} else if (strcmp(arg[iarg],"y") == 0) {
if (iarg+3 > narg) error->all("Illegal fix volume/rescale command");
if (domain->yperiodic == 0)
error->all("Cannot fix volume/rescale on a non-periodic boundary");
yflag = 1;
ylo_stop = atof(arg[iarg+1]);
yhi_stop = atof(arg[iarg+2]);
iarg += 3;
} else if (strcmp(arg[iarg],"z") == 0) {
if (iarg+3 > narg) error->all("Illegal fix volume/rescale command");
if (domain->zperiodic == 0)
error->all("Cannot fix volume/rescale on a non-periodic boundary");
zflag = 1;
zlo_stop = atof(arg[iarg+1]);
zhi_stop = atof(arg[iarg+2]);
iarg += 3;
} else error->all("Illegal fix volume/rescale command");
}
if (domain->triclinic)
error->all("Cannot use fix volume/rescale with triclinic box");
nrigid = 0;
rfix = NULL;
}
/* ---------------------------------------------------------------------- */
FixVolRescale::~FixVolRescale()
{
delete [] rfix;
}
/* ---------------------------------------------------------------------- */
int FixVolRescale::setmask()
{
int mask = 0;
mask |= END_OF_STEP;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixVolRescale::init()
{
xlo_start = domain->boxxlo;
xhi_start = domain->boxxhi;
ylo_start = domain->boxylo;
yhi_start = domain->boxyhi;
zlo_start = domain->boxzlo;
zhi_start = domain->boxzhi;
if (force->kspace) kspace_flag = 1;
else kspace_flag = 0;
// detect if any fix rigid exist so rigid bodies can be rescaled
// rfix[] = indices to each fix rigid
delete [] rfix;
nrigid = 0;
rfix = NULL;
for (int i = 0; i < modify->nfix; i++)
if (strcmp(modify->fix[i]->style,"rigid") == 0 ||
strcmp(modify->fix[i]->style,"poems") == 0) nrigid++;
if (nrigid) {
rfix = new int[nrigid];
nrigid = 0;
for (int i = 0; i < modify->nfix; i++)
if (strcmp(modify->fix[i]->style,"rigid") == 0 ||
strcmp(modify->fix[i]->style,"poems") == 0) rfix[nrigid++] = i;
}
}
/* ---------------------------------------------------------------------- */
void FixVolRescale::end_of_step()
{
int i;
double oldlo,oldhi,newlo,newhi,ratio;
double delta = update->ntimestep - update->beginstep;
delta /= update->endstep - update->beginstep;
double **x = atom->x;
int *mask = atom->mask;
int nlocal = atom->nlocal;
if (xflag) {
oldlo = domain->boxxlo;
oldhi = domain->boxxhi;
newlo = xlo_start + delta * (xlo_stop-xlo_start);
newhi = xhi_start + delta * (xhi_stop-xhi_start);
ratio = (newhi - newlo) / domain->xprd;
for (i = 0; i < nlocal; i++)
if (mask[i] & groupbit)
x[i][0] = newlo + (x[i][0] - oldlo) * ratio;
domain->boxxlo = newlo;
domain->boxxhi = newhi;
domain->xprd = newhi - newlo;
if (nrigid)
for (i = 0; i < nrigid; i++)
modify->fix[rfix[i]]->dilate(0,oldlo,oldhi,newlo,newhi);
}
if (yflag) {
oldlo = domain->boxylo;
oldhi = domain->boxyhi;
newlo = ylo_start + delta * (ylo_stop-ylo_start);
newhi = yhi_start + delta * (yhi_stop-yhi_start);
ratio = (newhi - newlo) / domain->yprd;
for (i = 0; i < nlocal; i++)
if (mask[i] & groupbit)
x[i][1] = newlo + (x[i][1] - oldlo) * ratio;
domain->boxylo = newlo;
domain->boxyhi = newhi;
domain->yprd = newhi - newlo;
if (nrigid)
for (i = 0; i < nrigid; i++)
modify->fix[rfix[i]]->dilate(1,oldlo,oldhi,newlo,newhi);
}
if (zflag) {
oldlo = domain->boxzlo;
oldhi = domain->boxzhi;
newlo = zlo_start + delta * (zlo_stop-zlo_start);
newhi = zhi_start + delta * (zhi_stop-zhi_start);
ratio = (newhi - newlo) / domain->zprd;
for (i = 0; i < nlocal; i++)
if (mask[i] & groupbit)
x[i][2] = newlo + (x[i][2] - oldlo) * ratio;
domain->boxzlo = newlo;
domain->boxzhi = newhi;
domain->zprd = newhi - newlo;
if (nrigid)
for (i = 0; i < nrigid; i++)
modify->fix[rfix[i]]->dilate(2,oldlo,oldhi,newlo,newhi);
}
// redo KSpace coeffs since volume has changed
if (kspace_flag) force->kspace->setup();
}

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