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lammps/src/fix_wall_harmonic.cpp
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fix_wall_harmonic.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 <math.h>
#include "fix_wall_harmonic.h"
#include "atom.h"
#include "error.h"
using namespace LAMMPS_NS;
using namespace FixConst;
/* ---------------------------------------------------------------------- */
FixWallHarmonic::FixWallHarmonic(LAMMPS *lmp, int narg, char **arg) :
FixWall(lmp, narg, arg) {}
/* ----------------------------------------------------------------------
interaction of all particles in group with a wall
m = index of wall coeffs
which = xlo,xhi,ylo,yhi,zlo,zhi
error if any particle is on or behind wall
------------------------------------------------------------------------- */
void FixWallHarmonic::wall_particle(int m, int which, double coord)
{
double delta,dr,fwall;
double vn;
double **x = atom->x;
double **f = atom->f;
int *mask = atom->mask;
int nlocal = atom->nlocal;
int dim = which / 2;
int side = which % 2;
if (side == 0) side = -1;
int onflag = 0;
for (int i = 0; i < nlocal; i++)
if (mask[i] & groupbit) {
if (side < 0) delta = x[i][dim] - coord;
else delta = coord - x[i][dim];
if (delta >= cutoff[m]) continue;
if (delta <= 0.0) {
onflag = 1;
continue;
}
dr = cutoff[m]-delta;
fwall = side * 2.0*epsilon[m]*dr;
f[i][dim] -= fwall;
ewall[0] += epsilon[m]*dr*dr;
ewall[m+1] += fwall;
if (evflag) {
if (side < 0) vn = -fwall*delta;
else vn = fwall*delta;
v_tally(dim, i, vn);
}
}
if (onflag) error->one(FLERR,"Particle on or inside fix wall surface");
}
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