Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F84862090
pair_born_coul_dsf_cs.cpp
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Wed, Sep 25, 07:31
Size
4 KB
Mime Type
text/x-c
Expires
Fri, Sep 27, 07:31 (2 d)
Engine
blob
Format
Raw Data
Handle
21022886
Attached To
rLAMMPS lammps
pair_born_coul_dsf_cs.cpp
View Options
/* ----------------------------------------------------------------------
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.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing author: Ariel Lozano (arielzn@gmail.com)
References: Fennell and Gezelter, JCP 124, 234104 (2006)
------------------------------------------------------------------------- */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pair_born_coul_dsf_cs.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "math_const.h"
#include "memory.h"
#include "error.h"
#include "math_special.h"
using namespace LAMMPS_NS;
using namespace MathConst;
#define EPSILON 1.0e-20
/* ---------------------------------------------------------------------- */
PairBornCoulDSFCS::PairBornCoulDSFCS(LAMMPS *lmp) : PairBornCoulDSF(lmp)
{
writedata = 1;
single_enable = 0;
}
/* ---------------------------------------------------------------------- */
void PairBornCoulDSFCS::compute(int eflag, int vflag)
{
int i,j,ii,jj,inum,jnum,itype,jtype;
double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
double r,rsq,r2inv,r6inv,forcecoul,forceborn,factor_coul,factor_lj;
double prefactor,erfcc,erfcd,arg;
double rexp;
int *ilist,*jlist,*numneigh,**firstneigh;
evdwl = ecoul = 0.0;
if (eflag || vflag) ev_setup(eflag,vflag);
else evflag = vflag_fdotr = 0;
double **x = atom->x;
double **f = atom->f;
double *q = atom->q;
int *type = atom->type;
int nlocal = atom->nlocal;
double *special_lj = force->special_lj;
double *special_coul = force->special_coul;
int newton_pair = force->newton_pair;
double qqrd2e = force->qqrd2e;
inum = list->inum;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
// loop over neighbors of my atoms
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
qtmp = q[i];
xtmp = x[i][0];
ytmp = x[i][1];
ztmp = x[i][2];
itype = type[i];
jlist = firstneigh[i];
jnum = numneigh[i];
// self coulombic energy
if (eflag) {
double e_self = -(e_shift/2.0 + alpha/MY_PIS) * qtmp*qtmp*qqrd2e;
ev_tally(i,i,nlocal,0,0.0,e_self,0.0,0.0,0.0,0.0);
}
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
factor_lj = special_lj[sbmask(j)];
factor_coul = special_coul[sbmask(j)];
j &= NEIGHMASK;
delx = xtmp - x[j][0];
dely = ytmp - x[j][1];
delz = ztmp - x[j][2];
rsq = delx*delx + dely*dely + delz*delz;
jtype = type[j];
if (rsq < cutsq[itype][jtype]) {
rsq += EPSILON; // Add Epsilon for case: r = 0; Interaction must be removed by special bond;
r2inv = 1.0/rsq;
if (rsq < cut_coulsq) {
r = sqrt(rsq);
prefactor = qqrd2e*qtmp*q[j] / r;
arg = alpha * r ;
erfcd = MathSpecial::expmsq(arg);
erfcc = MathSpecial::my_erfcx(arg) * erfcd;
forcecoul = prefactor * (erfcc/r + 2.0*alpha/MY_PIS * erfcd +
r*f_shift) * r;
if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;
} else forcecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
r6inv = r2inv*r2inv*r2inv;
r = sqrt(rsq);
rexp = exp((sigma[itype][jtype]-r)*rhoinv[itype][jtype]);
forceborn = born1[itype][jtype]*r*rexp - born2[itype][jtype]*r6inv
+ born3[itype][jtype]*r2inv*r6inv;
} else forceborn = 0.0;
fpair = (forcecoul + factor_lj*forceborn) * r2inv;
f[i][0] += delx*fpair;
f[i][1] += dely*fpair;
f[i][2] += delz*fpair;
if (newton_pair || j < nlocal) {
f[j][0] -= delx*fpair;
f[j][1] -= dely*fpair;
f[j][2] -= delz*fpair;
}
if (eflag) {
if (rsq < cut_coulsq) {
ecoul = prefactor * (erfcc - r*e_shift - rsq*f_shift);
if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
} else ecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
evdwl = a[itype][jtype]*rexp - c[itype][jtype]*r6inv +
d[itype][jtype]*r6inv*r2inv - offset[itype][jtype];
evdwl *= factor_lj;
} else evdwl = 0.0;
}
if (evflag) ev_tally(i,j,nlocal,newton_pair,
evdwl,ecoul,fpair,delx,dely,delz);
}
}
}
if (vflag_fdotr) virial_fdotr_compute();
}
Event Timeline
Log In to Comment