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pair_lj_cut_thole_long_omp.cpp
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Thu, Sep 5, 08:07

pair_lj_cut_thole_long_omp.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.
------------------------------------------------------------------------- */
/* ----------------------------------------------------------------------
Contributing author: Paul Crozier (SNL)
------------------------------------------------------------------------- */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pair_lj_cut_thole_long_omp.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "math_const.h"
#include "error.h"
#include "suffix.h"
using namespace LAMMPS_NS;
using namespace MathConst;
#define EWALD_F 1.12837917
#define EWALD_P 9.95473818e-1
#define B0 -0.1335096380159268
#define B1 -2.57839507e-1
#define B2 -1.37203639e-1
#define B3 -8.88822059e-3
#define B4 -5.80844129e-3
#define B5 1.14652755e-1
/* ---------------------------------------------------------------------- */
PairLJCutTholeLongOMP::PairLJCutTholeLongOMP(LAMMPS *lmp) :
PairLJCutTholeLong(lmp), ThrOMP(lmp, THR_PAIR)
{
suffix_flag |= Suffix::OMP;
respa_enable = 0;
cut_respa = NULL;
}
/* ---------------------------------------------------------------------- */
void PairLJCutTholeLongOMP::compute(int eflag, int vflag)
{
if (eflag || vflag) {
ev_setup(eflag,vflag);
} else evflag = vflag_fdotr = 0;
const int nall = atom->nlocal + atom->nghost;
const int nthreads = comm->nthreads;
const int inum = list->inum;
#if defined(_OPENMP)
#pragma omp parallel default(none) shared(eflag,vflag)
#endif
{
int ifrom, ito, tid;
loop_setup_thr(ifrom, ito, tid, inum, nthreads);
ThrData *thr = fix->get_thr(tid);
thr->timer(Timer::START);
ev_setup_thr(eflag, vflag, nall, eatom, vatom, thr);
if (evflag) {
if (eflag) {
if (force->newton_pair) eval<1,1,1>(ifrom, ito, thr);
else eval<1,1,0>(ifrom, ito, thr);
} else {
if (force->newton_pair) eval<1,0,1>(ifrom, ito, thr);
else eval<1,0,0>(ifrom, ito, thr);
}
} else {
if (force->newton_pair) eval<0,0,1>(ifrom, ito, thr);
else eval<0,0,0>(ifrom, ito, thr);
}
thr->timer(Timer::PAIR);
reduce_thr(this, eflag, vflag, thr);
} // end of omp parallel region
}
template <int EVFLAG, int EFLAG, int NEWTON_PAIR>
void PairLJCutTholeLongOMP::eval(int iifrom, int iito, ThrData * const thr)
{
const dbl3_t * _noalias const x = (dbl3_t *) atom->x[0];
dbl3_t * _noalias const f = (dbl3_t *) thr->get_f()[0];
const double * const q = atom->q;
const int * _noalias const type = atom->type;
const double * _noalias const special_lj = force->special_lj;
const double * _noalias const special_coul = force->special_coul;
const int * _noalias const ilist = list->ilist;
const int * _noalias const numneigh = list->numneigh;
const int * const * const firstneigh = list->firstneigh;
const int * _noalias const drudetype = fix_drude->drudetype;
const tagint * _noalias const drudeid = fix_drude->drudeid;
double xtmp,ytmp,ztmp,delx,dely,delz,fxtmp,fytmp,fztmp;
const int nlocal = atom->nlocal;
int j,jj,jnum,jtype,itable;
double ecoul,fpair,evdwl;
double r,rsq,r2inv,forcecoul,factor_coul,forcelj,factor_lj,r6inv;
double fraction,table;
double grij,expm2,prefactor,t,erfc,u;
double factor_f,factor_e;
int di,dj;
double qj,dqi,dqj,dcoul,asr,exp_asr;
int di_closest;
const double qqrd2e = force->qqrd2e;
evdwl = ecoul = 0.0;
// loop over neighbors of my atoms
for (int ii = iifrom; ii < iito; ii++) {
const int i = ilist[ii];
const double qi = q[i];
const int itype = type[i];
const int * _noalias const jlist = firstneigh[i];
const double * _noalias const cutsqi = cutsq[itype];
const double * _noalias const cut_ljsqi = cut_ljsq[itype];
const double * _noalias const offseti = offset[itype];
const double * _noalias const lj1i = lj1[itype];
const double * _noalias const lj2i = lj2[itype];
const double * _noalias const lj3i = lj3[itype];
const double * _noalias const lj4i = lj4[itype];
xtmp = x[i].x;
ytmp = x[i].y;
ztmp = x[i].z;
jnum = numneigh[i];
fxtmp=fytmp=fztmp=0.;
if (drudetype[type[i]] != NOPOL_TYPE){
di = atom->map(drudeid[i]);
if (di < 0) error->all(FLERR, "Drude partner not found");
di_closest = domain->closest_image(i, di);
if (drudetype[type[i]] == CORE_TYPE)
dqi = -q[di];
else
dqi = qi;
}
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].x;
dely = ytmp - x[j].y;
delz = ztmp - x[j].z;
rsq = delx*delx + dely*dely + delz*delz;
jtype = type[j];
if (rsq < cutsqi[jtype]) {
r2inv = 1.0/rsq;
if (rsq < cut_coulsq) {
qj = q[j];
r = sqrt(rsq);
if (!ncoultablebits || rsq <= tabinnersq) {
grij = g_ewald * r;
expm2 = exp(-grij*grij);
t = 1.0 / (1.0 + EWALD_P*grij);
u = 1. - t;
erfc = t * (1.+u*(B0+u*(B1+u*(B2+u*(B3+u*(B4+u*B5)))))) * expm2;
prefactor = qqrd2e * qi*qj/r;
forcecoul = prefactor * (erfc + EWALD_F*grij*expm2);
if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;
} else {
union_int_float_t rsq_lookup;
rsq_lookup.f = rsq;
itable = rsq_lookup.i & ncoulmask;
itable >>= ncoulshiftbits;
fraction = (rsq_lookup.f - rtable[itable]) * drtable[itable];
table = ftable[itable] + fraction*dftable[itable];
forcecoul = qi*qj * table;
if (factor_coul < 1.0) {
table = ctable[itable] + fraction*dctable[itable];
prefactor = qi*qj * table;
forcecoul -= (1.0-factor_coul)*prefactor;
}
}
if (drudetype[type[i]] != NOPOL_TYPE &&
drudetype[type[j]] != NOPOL_TYPE){
if (j != di_closest){
if (drudetype[type[j]] == CORE_TYPE){
dj = atom->map(drudeid[j]);
dqj = -q[dj];
} else dqj = qj;
asr = ascreen[type[i]][type[j]] * r;
exp_asr = exp(-asr);
dcoul = qqrd2e * dqi * dqj / r;
factor_f = 0.5*(2. + (exp_asr * (-2. - asr * (2. + asr))))
- factor_coul;
if (EFLAG) factor_e = 0.5*(2. - (exp_asr * (2. + asr)))
- factor_coul;
forcecoul += factor_f * dcoul;
}
}
} else forcecoul = 0.0;
if (rsq < cut_ljsqi[jtype]) {
r6inv = r2inv*r2inv*r2inv;
forcelj = r6inv * (lj1i[jtype]*r6inv - lj2i[jtype]);
} else forcelj = 0.0;
fpair = (forcecoul + factor_lj*forcelj) * r2inv;
fxtmp += delx*fpair;
fytmp += dely*fpair;
fztmp += delz*fpair;
if (NEWTON_PAIR || j < nlocal) {
f[j].x -= delx*fpair;
f[j].y -= dely*fpair;
f[j].z -= delz*fpair;
}
if (EFLAG) {
if (rsq < cut_coulsq) {
if (!ncoultablebits || rsq <= tabinnersq)
ecoul = prefactor*erfc;
else {
table = etable[itable] + fraction*detable[itable];
ecoul = qi*qj * table;
}
if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
if (drudetype[type[i]] != NOPOL_TYPE &&
drudetype[type[j]] != NOPOL_TYPE && j != di_closest){
ecoul += factor_e * dcoul;
}
} else ecoul = 0.0;
if (rsq < cut_ljsqi[jtype]) {
evdwl = r6inv*(lj3i[jtype]*r6inv-lj4i[jtype]) -
offseti[jtype];
evdwl *= factor_lj;
} else evdwl = 0.0;
}
if (EVFLAG) ev_tally_thr(this, i,j,nlocal,NEWTON_PAIR,
evdwl,ecoul,fpair,delx,dely,delz,thr);
}
}
f[i].x += fxtmp;
f[i].y += fytmp;
f[i].z += fztmp;
}
}

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