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displace_atoms.cpp
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Fri, Mar 7, 03:41

displace_atoms.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 "stdlib.h"
#include "string.h"
#include "displace_atoms.h"
#include "atom.h"
#include "domain.h"
#include "lattice.h"
#include "comm.h"
#include "group.h"
#include "error.h"
using namespace LAMMPS_NS;
#define MOVE 1
#define RAMP 2
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define MAX(a,b) ((a) > (b) ? (a) : (b))
/* ---------------------------------------------------------------------- */
DisplaceAtoms::DisplaceAtoms(LAMMPS *lmp) : Pointers(lmp) {}
/* ---------------------------------------------------------------------- */
void DisplaceAtoms::command(int narg, char **arg)
{
if (domain->box_exist == 0)
error->all("Displace_atoms command before simulation box is defined");
if (narg < 2) error->all("Illegal displace_atoms command");
// init entire system since comm->exchange is done
// comm::init needs neighbor::init needs pair::init needs kspace::init, etc
if (comm->me == 0 && screen)
fprintf(screen,"System init for displace_atoms ...\n");
lmp->init();
if (comm->me == 0 && screen) fprintf(screen,"Displacing atoms ...\n");
// group and style
int igroup = group->find(arg[0]);
if (igroup == -1) error->all("Could not find displace_atoms group ID");
int groupbit = group->bitmask[igroup];
int style;
if (strcmp(arg[1],"move") == 0) style = MOVE;
else if (strcmp(arg[1],"ramp") == 0) style = RAMP;
else error->all("Illegal displace_atoms command");
// set option defaults
scaleflag = 1;
// read options from end of input line
if (style == MOVE) options(narg-5,&arg[5]);
else if (style == RAMP) options(narg-8,&arg[8]);
// setup scaling
if (scaleflag && domain->lattice == NULL)
error->all("Use of displace_atoms with undefined lattice");
double xscale,yscale,zscale;
if (scaleflag) {
xscale = domain->lattice->xlattice;
yscale = domain->lattice->ylattice;
zscale = domain->lattice->zlattice;
}
else xscale = yscale = zscale = 1.0;
// move atoms directly by specified 3-vector distance
if (style == MOVE) {
double delx,dely,delz;
delx = xscale*atof(arg[2]);
dely = yscale*atof(arg[3]);
delz = zscale*atof(arg[4]);
double **x = atom->x;
int *mask = atom->mask;
int nlocal = atom->nlocal;
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
x[i][0] += delx;
x[i][1] += dely;
x[i][2] += delz;
}
}
// move atoms in ramped fashion
} else if (style == RAMP) {
int d_dim;
if (strcmp(arg[2],"x") == 0) d_dim = 0;
else if (strcmp(arg[2],"y") == 0) d_dim = 1;
else if (strcmp(arg[2],"z") == 0) d_dim = 2;
else error->all("Illegal displace_atoms ramp command");
double d_lo,d_hi;
if (d_dim == 0) {
d_lo = xscale*atof(arg[3]);
d_hi = xscale*atof(arg[4]);
} else if (d_dim == 1) {
d_lo = yscale*atof(arg[3]);
d_hi = yscale*atof(arg[4]);
} else if (d_dim == 2) {
d_lo = zscale*atof(arg[3]);
d_hi = zscale*atof(arg[4]);
}
int coord_dim;
if (strcmp(arg[5],"x") == 0) coord_dim = 0;
else if (strcmp(arg[5],"y") == 0) coord_dim = 1;
else if (strcmp(arg[5],"z") == 0) coord_dim = 2;
else error->all("Illegal velocity ramp command");
double coord_lo,coord_hi;
if (coord_dim == 0) {
coord_lo = xscale*atof(arg[6]);
coord_hi = xscale*atof(arg[7]);
} else if (coord_dim == 1) {
coord_lo = yscale*atof(arg[6]);
coord_hi = yscale*atof(arg[7]);
} else if (coord_dim == 2) {
coord_lo = zscale*atof(arg[6]);
coord_hi = zscale*atof(arg[7]);
}
double **x = atom->x;
int *mask = atom->mask;
int nlocal = atom->nlocal;
double fraction,dramp;
for (int i = 0; i < nlocal; i++) {
if (mask[i] & groupbit) {
fraction = (x[i][coord_dim] - coord_lo) / (coord_hi - coord_lo);
fraction = MAX(fraction,0.0);
fraction = MIN(fraction,1.0);
dramp = d_lo + fraction*(d_hi - d_lo);
x[i][d_dim] += dramp;
}
}
}
// move atoms to new processors
// enforce PBC before in case atoms are outside box
domain->pbc();
domain->reset_box();
comm->setup();
comm->exchange();
// check if any atoms were lost
double natoms;
double rlocal = atom->nlocal;
MPI_Allreduce(&rlocal,&natoms,1,MPI_DOUBLE,MPI_SUM,world);
if (natoms != atom->natoms) {
char str[128];
sprintf(str,"Lost atoms via displacement: original %.15g current %.15g",
atom->natoms,natoms);
error->all(str);
}
}
/* ----------------------------------------------------------------------
parse optional parameters at end of displace_atoms input line
------------------------------------------------------------------------- */
void DisplaceAtoms::options(int narg, char **arg)
{
if (narg < 0) error->all("Illegal displace_atoms command");
int iarg = 0;
while (iarg < narg) {
if (strcmp(arg[iarg],"units") == 0) {
if (iarg+2 > narg) error->all("Illegal displace_atoms command");
if (strcmp(arg[iarg+1],"box") == 0) scaleflag = 0;
else if (strcmp(arg[iarg+1],"lattice") == 0) scaleflag = 1;
else error->all("Illegal displace_atoms command");
iarg += 2;
} else error->all("Illegal displace_atoms command");
}
}

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