91 lines
2.6 KiB
C++
91 lines
2.6 KiB
C++
/* ----------------------------------------------------------------------
|
|
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
|
|
https://www.lammps.org/, Sandia National Laboratories
|
|
LAMMPS development team: developers@lammps.org
|
|
|
|
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 "fix_wall_morse.h"
|
|
#include "atom.h"
|
|
#include "error.h"
|
|
|
|
#include <cmath>
|
|
|
|
using namespace LAMMPS_NS;
|
|
|
|
/* ---------------------------------------------------------------------- */
|
|
|
|
FixWallMorse::FixWallMorse(LAMMPS *lmp, int narg, char **arg) : FixWall(lmp, narg, arg)
|
|
{
|
|
dynamic_group_allow = 1;
|
|
}
|
|
|
|
/* ---------------------------------------------------------------------- */
|
|
|
|
void FixWallMorse::precompute(int m)
|
|
{
|
|
coeff1[m] = 2.0 * epsilon[m] * alpha[m];
|
|
const double alpha_dr = -alpha[m] * (cutoff[m] - sigma[m]);
|
|
offset[m] = epsilon[m] * (exp(2.0 * alpha_dr) - 2.0 * exp(alpha_dr));
|
|
}
|
|
|
|
/* ----------------------------------------------------------------------
|
|
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 FixWallMorse::wall_particle(int m, int which, double coord)
|
|
{
|
|
double delta, 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;
|
|
}
|
|
double dr = delta - sigma[m];
|
|
double dexp = exp(-alpha[m] * dr);
|
|
fwall = side * coeff1[m] * (dexp * dexp - dexp);
|
|
ewall[0] += epsilon[m] * (dexp * dexp - 2.0 * dexp) - offset[m];
|
|
f[i][dim] -= fwall;
|
|
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");
|
|
}
|