228 lines
6.6 KiB
C++
228 lines
6.6 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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#include "math.h"
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#include "stdlib.h"
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#include "pair_lj_cut_coul_debye.h"
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#include "atom.h"
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#include "neigh_list.h"
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#include "force.h"
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#include "comm.h"
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#include "error.h"
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using namespace LAMMPS_NS;
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/* ---------------------------------------------------------------------- */
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PairLJCutCoulDebye::PairLJCutCoulDebye(LAMMPS *lmp) : PairLJCutCoulCut(lmp) {}
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/* ---------------------------------------------------------------------- */
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void PairLJCutCoulDebye::compute(int eflag, int vflag)
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{
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int i,j,ii,jj,inum,jnum,itype,jtype;
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double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
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double rsq,r2inv,r6inv,forcecoul,forcelj,factor_coul,factor_lj;
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double r,rinv,screening;
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int *ilist,*jlist,*numneigh,**firstneigh;
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evdwl = ecoul = 0.0;
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if (eflag || vflag) ev_setup(eflag,vflag);
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else evflag = vflag_fdotr = 0;
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double **x = atom->x;
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double **f = atom->f;
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double *q = atom->q;
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int *type = atom->type;
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int nlocal = atom->nlocal;
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int nall = nlocal + atom->nghost;
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double *special_coul = force->special_coul;
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double *special_lj = force->special_lj;
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int newton_pair = force->newton_pair;
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double qqrd2e = force->qqrd2e;
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inum = list->inum;
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ilist = list->ilist;
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numneigh = list->numneigh;
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firstneigh = list->firstneigh;
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// loop over neighbors of my atoms
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for (ii = 0; ii < inum; ii++) {
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i = ilist[ii];
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qtmp = q[i];
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xtmp = x[i][0];
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ytmp = x[i][1];
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ztmp = x[i][2];
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itype = type[i];
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jlist = firstneigh[i];
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jnum = numneigh[i];
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for (jj = 0; jj < jnum; jj++) {
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j = jlist[jj];
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if (j < nall) factor_coul = factor_lj = 1.0;
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else {
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factor_coul = special_coul[j/nall];
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factor_lj = special_lj[j/nall];
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j %= nall;
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}
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delx = xtmp - x[j][0];
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dely = ytmp - x[j][1];
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delz = ztmp - x[j][2];
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rsq = delx*delx + dely*dely + delz*delz;
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jtype = type[j];
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if (rsq < cutsq[itype][jtype]) {
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r2inv = 1.0/rsq;
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if (rsq < cut_coulsq[itype][jtype]) {
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r = sqrt(rsq);
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rinv = 1.0/r;
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screening = exp(-kappa*r);
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forcecoul = qqrd2e * qtmp*q[j] * screening * (kappa + rinv);
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} else forcecoul = 0.0;
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if (rsq < cut_ljsq[itype][jtype]) {
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r6inv = r2inv*r2inv*r2inv;
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forcelj = r6inv * (lj1[itype][jtype]*r6inv - lj2[itype][jtype]);
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} else forcelj = 0.0;
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fpair = (factor_coul*forcecoul + factor_lj*forcelj) * r2inv;
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f[i][0] += delx*fpair;
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f[i][1] += dely*fpair;
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f[i][2] += delz*fpair;
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if (newton_pair || j < nlocal) {
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f[j][0] -= delx*fpair;
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f[j][1] -= dely*fpair;
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f[j][2] -= delz*fpair;
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}
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if (eflag) {
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if (rsq < cut_coulsq[itype][jtype])
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ecoul = factor_coul * qqrd2e * qtmp*q[j] * rinv * screening;
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else ecoul = 0.0;
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if (rsq < cut_ljsq[itype][jtype]) {
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evdwl = r6inv*(lj3[itype][jtype]*r6inv-lj4[itype][jtype]) -
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offset[itype][jtype];
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evdwl *= factor_lj;
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} else evdwl = 0.0;
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}
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if (evflag) ev_tally(i,j,nlocal,newton_pair,
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evdwl,ecoul,fpair,delx,dely,delz);
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}
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}
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}
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if (vflag_fdotr) virial_compute();
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}
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/* ----------------------------------------------------------------------
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global settings
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------------------------------------------------------------------------- */
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void PairLJCutCoulDebye::settings(int narg, char **arg)
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{
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if (narg < 2 || narg > 3) error->all("Illegal pair_style command");
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kappa = force->numeric(arg[0]);
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cut_lj_global = force->numeric(arg[1]);
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if (narg == 2) cut_coul_global = cut_lj_global;
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else cut_coul_global = force->numeric(arg[2]);
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// reset cutoffs that were previously set from data file
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if (allocated) {
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int i,j;
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for (i = 1; i <= atom->ntypes; i++)
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for (j = i+1; j <= atom->ntypes; j++)
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if (setflag[i][j] == 1) {
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cut_lj[i][j] = cut_lj_global;
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cut_coul[i][j] = cut_coul_global;
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}
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}
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}
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/* ----------------------------------------------------------------------
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proc 0 writes to restart file
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------------------------------------------------------------------------- */
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void PairLJCutCoulDebye::write_restart_settings(FILE *fp)
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{
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fwrite(&cut_lj_global,sizeof(double),1,fp);
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fwrite(&cut_coul_global,sizeof(double),1,fp);
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fwrite(&kappa,sizeof(double),1,fp);
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fwrite(&offset_flag,sizeof(int),1,fp);
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fwrite(&mix_flag,sizeof(int),1,fp);
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}
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/* ----------------------------------------------------------------------
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proc 0 reads from restart file, bcasts
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------------------------------------------------------------------------- */
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void PairLJCutCoulDebye::read_restart_settings(FILE *fp)
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{
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if (comm->me == 0) {
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fread(&cut_lj_global,sizeof(double),1,fp);
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fread(&cut_coul_global,sizeof(double),1,fp);
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fread(&kappa,sizeof(double),1,fp);
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fread(&offset_flag,sizeof(int),1,fp);
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fread(&mix_flag,sizeof(int),1,fp);
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}
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MPI_Bcast(&cut_lj_global,1,MPI_DOUBLE,0,world);
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MPI_Bcast(&cut_coul_global,1,MPI_DOUBLE,0,world);
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MPI_Bcast(&kappa,1,MPI_DOUBLE,0,world);
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MPI_Bcast(&offset_flag,1,MPI_INT,0,world);
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MPI_Bcast(&mix_flag,1,MPI_INT,0,world);
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}
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/* ---------------------------------------------------------------------- */
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double PairLJCutCoulDebye::single(int i, int j, int itype, int jtype,
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double rsq,
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double factor_coul, double factor_lj,
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double &fforce)
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{
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double r2inv,r6inv,r,rinv,screening,forcecoul,forcelj,phicoul,philj;
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r2inv = 1.0/rsq;
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if (rsq < cut_coulsq[itype][jtype]) {
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r = sqrt(rsq);
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rinv = 1.0/r;
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screening = exp(-kappa*r);
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forcecoul = force->qqrd2e * atom->q[i]*atom->q[j] *
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screening * (kappa + rinv);
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} else forcecoul = 0.0;
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if (rsq < cut_ljsq[itype][jtype]) {
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r6inv = r2inv*r2inv*r2inv;
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forcelj = r6inv * (lj1[itype][jtype]*r6inv - lj2[itype][jtype]);
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} else forcelj = 0.0;
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fforce = (factor_coul*forcecoul + factor_lj*forcelj) * r2inv;
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double eng = 0.0;
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if (rsq < cut_coulsq[itype][jtype]) {
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phicoul = force->qqrd2e * atom->q[i]*atom->q[j] * rinv * screening;
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eng += factor_coul*phicoul;
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}
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if (rsq < cut_ljsq[itype][jtype]) {
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philj = r6inv*(lj3[itype][jtype]*r6inv-lj4[itype][jtype]) -
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offset[itype][jtype];
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eng += factor_lj*philj;
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}
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return eng;
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}
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