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fix_setforce.cpp
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Sat, Jul 5, 21:37

fix_setforce.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_setforce.h"
#include "atom.h"
#include "update.h"
#include "modify.h"
#include "domain.h"
#include "region.h"
#include "respa.h"
#include "input.h"
#include "variable.h"
#include "memory.h"
#include "error.h"
#include "force.h"
using namespace LAMMPS_NS;
using namespace FixConst;
enum{NONE,CONSTANT,EQUAL,ATOM};
/* ---------------------------------------------------------------------- */
FixSetForce::FixSetForce(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg),
xstr(NULL), ystr(NULL), zstr(NULL), idregion(NULL), sforce(NULL)
{
if (narg < 6) error->all(FLERR,"Illegal fix setforce command");
dynamic_group_allow = 1;
vector_flag = 1;
size_vector = 3;
global_freq = 1;
extvector = 1;
respa_level_support = 1;
ilevel_respa = nlevels_respa = 0;
xstr = ystr = zstr = NULL;
if (strstr(arg[3],"v_") == arg[3]) {
int n = strlen(&arg[3][2]) + 1;
xstr = new char[n];
strcpy(xstr,&arg[3][2]);
} else if (strcmp(arg[3],"NULL") == 0) {
xstyle = NONE;
} else {
xvalue = force->numeric(FLERR,arg[3]);
xstyle = CONSTANT;
}
if (strstr(arg[4],"v_") == arg[4]) {
int n = strlen(&arg[4][2]) + 1;
ystr = new char[n];
strcpy(ystr,&arg[4][2]);
} else if (strcmp(arg[4],"NULL") == 0) {
ystyle = NONE;
} else {
yvalue = force->numeric(FLERR,arg[4]);
ystyle = CONSTANT;
}
if (strstr(arg[5],"v_") == arg[5]) {
int n = strlen(&arg[5][2]) + 1;
zstr = new char[n];
strcpy(zstr,&arg[5][2]);
} else if (strcmp(arg[5],"NULL") == 0) {
zstyle = NONE;
} else {
zvalue = force->numeric(FLERR,arg[5]);
zstyle = CONSTANT;
}
// optional args
iregion = -1;
idregion = NULL;
int iarg = 6;
while (iarg < narg) {
if (strcmp(arg[iarg],"region") == 0) {
if (iarg+2 > narg) error->all(FLERR,"Illegal fix setforce command");
iregion = domain->find_region(arg[iarg+1]);
if (iregion == -1)
error->all(FLERR,"Region ID for fix setforce does not exist");
int n = strlen(arg[iarg+1]) + 1;
idregion = new char[n];
strcpy(idregion,arg[iarg+1]);
iarg += 2;
} else error->all(FLERR,"Illegal fix setforce command");
}
force_flag = 0;
foriginal[0] = foriginal[1] = foriginal[2] = 0.0;
maxatom = 1;
memory->create(sforce,maxatom,3,"setforce:sforce");
}
/* ---------------------------------------------------------------------- */
FixSetForce::~FixSetForce()
{
if (copymode) return;
delete [] xstr;
delete [] ystr;
delete [] zstr;
delete [] idregion;
memory->destroy(sforce);
}
/* ---------------------------------------------------------------------- */
int FixSetForce::setmask()
{
int mask = 0;
mask |= POST_FORCE;
mask |= POST_FORCE_RESPA;
mask |= MIN_POST_FORCE;
return mask;
}
/* ---------------------------------------------------------------------- */
void FixSetForce::init()
{
// check variables
if (xstr) {
xvar = input->variable->find(xstr);
if (xvar < 0)
error->all(FLERR,"Variable name for fix setforce does not exist");
if (input->variable->equalstyle(xvar)) xstyle = EQUAL;
else if (input->variable->atomstyle(xvar)) xstyle = ATOM;
else error->all(FLERR,"Variable for fix setforce is invalid style");
}
if (ystr) {
yvar = input->variable->find(ystr);
if (yvar < 0)
error->all(FLERR,"Variable name for fix setforce does not exist");
if (input->variable->equalstyle(yvar)) ystyle = EQUAL;
else if (input->variable->atomstyle(yvar)) ystyle = ATOM;
else error->all(FLERR,"Variable for fix setforce is invalid style");
}
if (zstr) {
zvar = input->variable->find(zstr);
if (zvar < 0)
error->all(FLERR,"Variable name for fix setforce does not exist");
if (input->variable->equalstyle(zvar)) zstyle = EQUAL;
else if (input->variable->atomstyle(zvar)) zstyle = ATOM;
else error->all(FLERR,"Variable for fix setforce is invalid style");
}
// set index and check validity of region
if (iregion >= 0) {
iregion = domain->find_region(idregion);
if (iregion == -1)
error->all(FLERR,"Region ID for fix setforce does not exist");
}
if (xstyle == ATOM || ystyle == ATOM || zstyle == ATOM)
varflag = ATOM;
else if (xstyle == EQUAL || ystyle == EQUAL || zstyle == EQUAL)
varflag = EQUAL;
else varflag = CONSTANT;
if (strstr(update->integrate_style,"respa")) {
nlevels_respa = ((Respa *) update->integrate)->nlevels;
if (respa_level >= 0) ilevel_respa = MIN(respa_level,nlevels_respa-1);
else ilevel_respa = nlevels_respa-1;
}
// cannot use non-zero forces for a minimization since no energy is integrated
// use fix addforce instead
int flag = 0;
if (update->whichflag == 2) {
if (xstyle == EQUAL || xstyle == ATOM) flag = 1;
if (ystyle == EQUAL || ystyle == ATOM) flag = 1;
if (zstyle == EQUAL || zstyle == ATOM) flag = 1;
if (xstyle == CONSTANT && xvalue != 0.0) flag = 1;
if (ystyle == CONSTANT && yvalue != 0.0) flag = 1;
if (zstyle == CONSTANT && zvalue != 0.0) flag = 1;
}
if (flag)
error->all(FLERR,"Cannot use non-zero forces in an energy minimization");
}
/* ---------------------------------------------------------------------- */
void FixSetForce::setup(int vflag)
{
if (strstr(update->integrate_style,"verlet"))
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 FixSetForce::min_setup(int vflag)
{
post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixSetForce::post_force(int vflag)
{
double **x = atom->x;
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
// update region if necessary
Region *region = NULL;
if (iregion >= 0) {
region = domain->regions[iregion];
region->prematch();
}
// reallocate sforce array if necessary
if (varflag == ATOM && atom->nmax > maxatom) {
maxatom = atom->nmax;
memory->destroy(sforce);
memory->create(sforce,maxatom,3,"setforce:sforce");
}
foriginal[0] = foriginal[1] = foriginal[2] = 0.0;
force_flag = 0;
if (varflag == CONSTANT) {
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
if (region && !region->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];
if (xstyle) f[i][0] = xvalue;
if (ystyle) f[i][1] = yvalue;
if (zstyle) f[i][2] = zvalue;
}
// variable force, wrap with clear/add
} else {
modify->clearstep_compute();
if (xstyle == EQUAL) xvalue = input->variable->compute_equal(xvar);
else if (xstyle == ATOM)
input->variable->compute_atom(xvar,igroup,&sforce[0][0],3,0);
if (ystyle == EQUAL) yvalue = input->variable->compute_equal(yvar);
else if (ystyle == ATOM)
input->variable->compute_atom(yvar,igroup,&sforce[0][1],3,0);
if (zstyle == EQUAL) zvalue = input->variable->compute_equal(zvar);
else if (zstyle == ATOM)
input->variable->compute_atom(zvar,igroup,&sforce[0][2],3,0);
modify->addstep_compute(update->ntimestep + 1);
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
if (region && !region->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];
if (xstyle == ATOM) f[i][0] = sforce[i][0];
else if (xstyle) f[i][0] = xvalue;
if (ystyle == ATOM) f[i][1] = sforce[i][1];
else if (ystyle) f[i][1] = yvalue;
if (zstyle == ATOM) f[i][2] = sforce[i][2];
else if (zstyle) f[i][2] = zvalue;
}
}
}
/* ---------------------------------------------------------------------- */
void FixSetForce::post_force_respa(int vflag, int ilevel, int iloop)
{
// set force to desired value on requested level, 0.0 on other levels
if (ilevel == ilevel_respa) post_force(vflag);
else {
Region *region = NULL;
if (iregion >= 0) {
region = domain->regions[iregion];
region->prematch();
}
double **x = atom->x;
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
if (region && !region->match(x[i][0],x[i][1],x[i][2])) continue;
if (xstyle) f[i][0] = 0.0;
if (ystyle) f[i][1] = 0.0;
if (zstyle) f[i][2] = 0.0;
}
}
}
/* ---------------------------------------------------------------------- */
void FixSetForce::min_post_force(int vflag)
{
post_force(vflag);
}
/* ----------------------------------------------------------------------
return components of total force on fix group before force was changed
------------------------------------------------------------------------- */
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];
}
/* ----------------------------------------------------------------------
memory usage of local atom-based array
------------------------------------------------------------------------- */
double FixSetForce::memory_usage()
{
double bytes = 0.0;
if (varflag == ATOM) bytes = maxatom*3 * sizeof(double);
return bytes;
}

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