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fix_external.cpp
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Tue, Oct 8, 23:56

fix_external.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 <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "fix_external.h"
#include "atom.h"
#include "update.h"
#include "memory.h"
#include "error.h"
#include "force.h"
using namespace LAMMPS_NS;
using namespace FixConst;
enum{PF_CALLBACK,PF_ARRAY};
/* ---------------------------------------------------------------------- */
FixExternal::FixExternal(LAMMPS *lmp, int narg, char **arg) :
Fix(lmp, narg, arg)
{
if (narg < 4) error->all(FLERR,"Illegal fix external command");
scalar_flag = 1;
global_freq = 1;
extscalar = 1;
if (strcmp(arg[3],"pf/callback") == 0) {
if (narg != 6) error->all(FLERR,"Illegal fix external command");
mode = PF_CALLBACK;
ncall = force->inumeric(FLERR,arg[4]);
napply = force->inumeric(FLERR,arg[5]);
if (ncall <= 0 || napply <= 0)
error->all(FLERR,"Illegal fix external command");
} else if (strcmp(arg[3],"pf/array") == 0) {
if (narg != 5) error->all(FLERR,"Illegal fix external command");
mode = PF_ARRAY;
napply = force->inumeric(FLERR,arg[4]);
if (napply <= 0) error->all(FLERR,"Illegal fix external command");
} else error->all(FLERR,"Illegal fix external command");
callback = NULL;
// perform initial allocation of atom-based array
// register with Atom class
fexternal = NULL;
grow_arrays(atom->nmax);
atom->add_callback(0);
user_energy = 0.0;
}
/* ---------------------------------------------------------------------- */
FixExternal::~FixExternal()
{
// unregister callbacks to this fix from Atom class
atom->delete_callback(id,0);
memory->destroy(fexternal);
}
/* ---------------------------------------------------------------------- */
int FixExternal::setmask()
{
int mask = 0;
if (mode == PF_CALLBACK || mode == PF_ARRAY) {
mask |= POST_FORCE;
mask |= THERMO_ENERGY;
mask |= MIN_POST_FORCE;
}
return mask;
}
/* ---------------------------------------------------------------------- */
void FixExternal::init()
{
if (mode == PF_CALLBACK && callback == NULL)
error->all(FLERR,"Fix external callback function not set");
}
/* ---------------------------------------------------------------------- */
void FixExternal::setup(int vflag)
{
post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixExternal::min_setup(int vflag)
{
post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixExternal::post_force(int vflag)
{
bigint ntimestep = update->ntimestep;
// invoke the callback in driver program
// it will fill fexternal with forces
if (mode == PF_CALLBACK && ntimestep % ncall == 0)
(this->callback)(ptr_caller,update->ntimestep,
atom->nlocal,atom->tag,atom->x,fexternal);
// add forces from fexternal to atoms in group
if (ntimestep % napply == 0) {
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
f[i][0] += fexternal[i][0];
f[i][1] += fexternal[i][1];
f[i][2] += fexternal[i][2];
}
}
}
/* ---------------------------------------------------------------------- */
void FixExternal::min_post_force(int vflag)
{
post_force(vflag);
}
/* ---------------------------------------------------------------------- */
void FixExternal::set_energy(double eng)
{
user_energy = eng;
}
/* ----------------------------------------------------------------------
potential energy of added force
up to user to set it via set_energy()
------------------------------------------------------------------------- */
double FixExternal::compute_scalar()
{
return user_energy;
}
/* ----------------------------------------------------------------------
memory usage of local atom-based array
------------------------------------------------------------------------- */
double FixExternal::memory_usage()
{
double bytes = 3*atom->nmax * sizeof(double);
return bytes;
}
/* ----------------------------------------------------------------------
allocate atom-based array
------------------------------------------------------------------------- */
void FixExternal::grow_arrays(int nmax)
{
memory->grow(fexternal,nmax,3,"external:fexternal");
}
/* ----------------------------------------------------------------------
copy values within local atom-based array
------------------------------------------------------------------------- */
void FixExternal::copy_arrays(int i, int j, int delflag)
{
fexternal[j][0] = fexternal[i][0];
fexternal[j][1] = fexternal[i][1];
fexternal[j][2] = fexternal[i][2];
}
/* ----------------------------------------------------------------------
pack values in local atom-based array for exchange with another proc
------------------------------------------------------------------------- */
int FixExternal::pack_exchange(int i, double *buf)
{
buf[0] = fexternal[i][0];
buf[1] = fexternal[i][1];
buf[2] = fexternal[i][2];
return 3;
}
/* ----------------------------------------------------------------------
unpack values in local atom-based array from exchange with another proc
------------------------------------------------------------------------- */
int FixExternal::unpack_exchange(int nlocal, double *buf)
{
fexternal[nlocal][0] = buf[0];
fexternal[nlocal][1] = buf[1];
fexternal[nlocal][2] = buf[2];
return 3;
}
/* ----------------------------------------------------------------------
external caller sets a callback function to invoke in post_force()
------------------------------------------------------------------------- */
void FixExternal::set_callback(FnPtr caller_callback, void *caller_ptr)
{
callback = caller_callback;
ptr_caller = caller_ptr;
}

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