forked from lijiext/lammps
94 lines
2.9 KiB
C++
94 lines
2.9 KiB
C++
/* ----------------------------------------------------------------------
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LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
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http://lammps.sandia.gov, Sandia National Laboratories
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Steve Plimpton, sjplimp@sandia.gov
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Copyright (2003) Sandia Corporation. Under the terms of Contract
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DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
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certain rights in this software. This software is distributed under
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the GNU General Public License.
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See the README file in the top-level LAMMPS directory.
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------------------------------------------------------------------------- */
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/* ----------------------------------------------------------------------
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Contributing author: Jonathan Lee (Sandia)
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------------------------------------------------------------------------- */
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#include "fix_wall_lj1043.h"
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#include <cmath>
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#include "atom.h"
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#include "math_const.h"
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using namespace LAMMPS_NS;
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using namespace MathConst;
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/* ---------------------------------------------------------------------- */
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FixWallLJ1043::FixWallLJ1043(LAMMPS *lmp, int narg, char **arg) :
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FixWall(lmp, narg, arg)
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{
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dynamic_group_allow = 1;
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}
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/* ---------------------------------------------------------------------- */
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void FixWallLJ1043::precompute(int m)
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{
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coeff1[m] = MY_2PI * 2.0/5.0 * epsilon[m] * pow(sigma[m],10.0);
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coeff2[m] = MY_2PI * epsilon[m] * pow(sigma[m],4.0);
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coeff3[m] = MY_2PI * pow(2.0,1/2.0) / 3 * epsilon[m] * pow(sigma[m],3.0);
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coeff4[m] = 0.61 / pow(2.0,1/2.0) * sigma[m];
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coeff5[m] = coeff1[m] * 10.0;
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coeff6[m] = coeff2[m] * 4.0;
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coeff7[m] = coeff3[m] * 3.0;
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double rinv = 1.0/cutoff[m];
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double r2inv = rinv*rinv;
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double r4inv = r2inv*r2inv;
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offset[m] = coeff1[m]*r4inv*r4inv*r2inv - coeff2[m]*r4inv -
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coeff3[m]*pow(cutoff[m]+coeff4[m],-3.0);
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}
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/* ---------------------------------------------------------------------- */
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void FixWallLJ1043::wall_particle(int m, int which, double coord)
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{
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double delta,rinv,r2inv,r4inv,r10inv,fwall;
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double vn;
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double **x = atom->x;
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double **f = atom->f;
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int *mask = atom->mask;
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int nlocal = atom->nlocal;
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int dim = which / 2;
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int side = which % 2;
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if (side == 0) side = -1;
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for (int i = 0; i < nlocal; i++)
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if (mask[i] & groupbit) {
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if (side < 0) delta = x[i][dim] - coord;
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else delta = coord - x[i][dim];
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if (delta <= 0.0) continue;
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if (delta > cutoff[m]) continue;
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rinv = 1.0/delta;
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r2inv = rinv*rinv;
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r4inv = r2inv*r2inv;
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r10inv = r4inv*r4inv*r2inv;
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fwall = side * (coeff5[m]*r10inv*rinv - coeff6[m]*r4inv*rinv -
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coeff7[m]*pow(delta+coeff4[m],-4.0));
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f[i][dim] -= fwall;
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ewall[0] += coeff1[m]*r10inv - coeff2[m]*r4inv -
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coeff3[m]*pow(delta+coeff4[m],-3.0) - offset[m];
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ewall[m+1] += fwall;
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if (evflag) {
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if (side < 0) vn = -fwall*delta;
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else vn = fwall*delta;
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v_tally(dim, i, vn);
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}
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}
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}
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