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pair_lj_sdk_coul_msm.cpp
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Thu, Jul 4, 02:12

pair_lj_sdk_coul_msm.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: Axel Kohlmeyer (Temple U)
This style is a simplified re-implementation of the CG/CMM pair style
------------------------------------------------------------------------- */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pair_lj_sdk_coul_msm.h"
#include "atom.h"
#include "comm.h"
#include "force.h"
#include "kspace.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "update.h"
#include "integrate.h"
#include "math_const.h"
#include "memory.h"
#include "error.h"
#include "lj_sdk_common.h"
using namespace LAMMPS_NS;
using namespace MathConst;
using namespace LJSDKParms;
/* ---------------------------------------------------------------------- */
PairLJSDKCoulMSM::PairLJSDKCoulMSM(LAMMPS *lmp) : PairLJSDKCoulLong(lmp)
{
ewaldflag = pppmflag = 0;
msmflag = 1;
respa_enable = 0;
ftable = NULL;
}
/* ---------------------------------------------------------------------- */
void PairLJSDKCoulMSM::compute(int eflag, int vflag)
{
if (force->kspace->scalar_pressure_flag)
error->all(FLERR,"Must use 'kspace_modify pressure/scalar no' with Pair style");
if (eflag || vflag) {
ev_setup(eflag,vflag);
} else evflag = vflag_fdotr = 0;
if (evflag) {
if (eflag) {
if (force->newton_pair) eval_msm<1,1,1>();
else eval_msm<1,1,0>();
} else {
if (force->newton_pair) eval_msm<1,0,1>();
else eval_msm<1,0,0>();
}
} else {
if (force->newton_pair) eval_msm<0,0,1>();
else eval_msm<0,0,0>();
}
if (vflag_fdotr) virial_fdotr_compute();
}
/* ---------------------------------------------------------------------- */
template <int EVFLAG, int EFLAG, int NEWTON_PAIR>
void PairLJSDKCoulMSM::eval_msm()
{
int i,ii,j,jj,jtype,itable;
double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
double fraction,table;
double r,rsq,r2inv,forcecoul,forcelj,factor_coul,factor_lj;
double egamma,fgamma,prefactor;
const double * const * const x = atom->x;
double * const * const f = atom->f;
const double * const q = atom->q;
const int * const type = atom->type;
const int nlocal = atom->nlocal;
const double * const special_coul = force->special_coul;
const double * const special_lj = force->special_lj;
const double qqrd2e = force->qqrd2e;
double fxtmp,fytmp,fztmp;
const int inum = list->inum;
const int * const ilist = list->ilist;
const int * const numneigh = list->numneigh;
const int * const * const 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];
fxtmp=fytmp=fztmp=0.0;
const int itype = type[i];
const int * const jlist = firstneigh[i];
const int jnum = numneigh[i];
for (jj = 0; jj < jnum; jj++) {
forcecoul = forcelj = evdwl = ecoul = 0.0;
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]) {
r2inv = 1.0/rsq;
const int ljt = lj_type[itype][jtype];
if (rsq < cut_coulsq) {
if (!ncoultablebits || rsq <= tabinnersq) {
r = sqrt(rsq);
prefactor = qqrd2e * qtmp*q[j]/r;
fgamma = 1.0 + (rsq/cut_coulsq)*force->kspace->dgamma(r/cut_coul);
forcecoul = prefactor * fgamma;
if (EFLAG) {
egamma = 1.0 - (r/cut_coul)*force->kspace->gamma(r/cut_coul);
ecoul = prefactor*egamma;
}
if (factor_coul < 1.0) {
forcecoul -= (1.0-factor_coul)*prefactor;
if (EFLAG) ecoul -= (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 = qtmp*q[j] * table;
if (EFLAG) ecoul = qtmp*q[j] *
(etable[itable] + fraction*detable[itable]);
if (factor_coul < 1.0) {
table = ctable[itable] + fraction*dctable[itable];
prefactor = qtmp*q[j] * table;
forcecoul -= (1.0-factor_coul)*prefactor;
if (EFLAG) ecoul -= (1.0-factor_coul)*prefactor;
}
}
} else forcecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
if (ljt == LJ12_4) {
const double r4inv=r2inv*r2inv;
forcelj = r4inv*(lj1[itype][jtype]*r4inv*r4inv
- lj2[itype][jtype]);
if (EFLAG)
evdwl = r4inv*(lj3[itype][jtype]*r4inv*r4inv
- lj4[itype][jtype]) - offset[itype][jtype];
} else if (ljt == LJ9_6) {
const double r3inv = r2inv*sqrt(r2inv);
const double r6inv = r3inv*r3inv;
forcelj = r6inv*(lj1[itype][jtype]*r3inv
- lj2[itype][jtype]);
if (EFLAG)
evdwl = r6inv*(lj3[itype][jtype]*r3inv
- lj4[itype][jtype]) - offset[itype][jtype];
} else if (ljt == LJ12_6) {
const double r6inv = r2inv*r2inv*r2inv;
forcelj = r6inv*(lj1[itype][jtype]*r6inv
- lj2[itype][jtype]);
if (EFLAG)
evdwl = r6inv*(lj3[itype][jtype]*r6inv
- lj4[itype][jtype]) - offset[itype][jtype];
}
forcelj *= factor_lj;
if (EFLAG) evdwl *= factor_lj;
}
fpair = (forcecoul + forcelj) * r2inv;
fxtmp += delx*fpair;
fytmp += dely*fpair;
fztmp += delz*fpair;
if (NEWTON_PAIR || j < nlocal) {
f[j][0] -= delx*fpair;
f[j][1] -= dely*fpair;
f[j][2] -= delz*fpair;
}
if (EVFLAG) ev_tally(i,j,nlocal,NEWTON_PAIR,
evdwl,ecoul,fpair,delx,dely,delz);
}
}
f[i][0] += fxtmp;
f[i][1] += fytmp;
f[i][2] += fztmp;
}
}
/* ---------------------------------------------------------------------- */
double PairLJSDKCoulMSM::single(int i, int j, int itype, int jtype,
double rsq,
double factor_coul, double factor_lj,
double &fforce)
{
double r2inv,r,fgamma,egamma,prefactor;
double fraction,table,forcecoul,forcelj,phicoul,philj;
int itable;
forcecoul = forcelj = phicoul = philj = 0.0;
r2inv = 1.0/rsq;
if (rsq < cut_coulsq) {
if (!ncoultablebits || rsq <= tabinnersq) {
r = sqrt(rsq);
prefactor = force->qqrd2e * atom->q[i]*atom->q[j]/r;
egamma = 1.0 - (r/cut_coul)*force->kspace->gamma(r/cut_coul);
fgamma = 1.0 + (rsq/cut_coulsq)*force->kspace->dgamma(r/cut_coul);
forcecoul = prefactor * fgamma;
phicoul = prefactor * egamma;
if (factor_coul < 1.0) {
forcecoul -= (1.0-factor_coul)*prefactor;
phicoul -= (1.0-factor_coul)*prefactor;
}
} else {
union_int_float_t rsq_lookup_single;
rsq_lookup_single.f = rsq;
itable = rsq_lookup_single.i & ncoulmask;
itable >>= ncoulshiftbits;
fraction = (rsq_lookup_single.f - rtable[itable]) * drtable[itable];
table = ftable[itable] + fraction*dftable[itable];
forcecoul = atom->q[i]*atom->q[j] * table;
table = etable[itable] + fraction*detable[itable];
phicoul = atom->q[i]*atom->q[j] * table;
if (factor_coul < 1.0) {
table = ctable[itable] + fraction*dctable[itable];
prefactor = atom->q[i]*atom->q[j] * table;
forcecoul -= (1.0-factor_coul)*prefactor;
phicoul -= (1.0-factor_coul)*prefactor;
}
}
}
if (rsq < cut_ljsq[itype][jtype]) {
const int ljt = lj_type[itype][jtype];
const double ljpow1 = lj_pow1[ljt];
const double ljpow2 = lj_pow2[ljt];
const double ljpref = lj_prefact[ljt];
const double ratio = sigma[itype][jtype]/sqrt(rsq);
const double eps = epsilon[itype][jtype];
forcelj = factor_lj * ljpref*eps * (ljpow1*pow(ratio,ljpow1)
- ljpow2*pow(ratio,ljpow2))/rsq;
philj = factor_lj * (ljpref*eps * (pow(ratio,ljpow1) - pow(ratio,ljpow2))
- offset[itype][jtype]);
}
fforce = (forcecoul + forcelj) * r2inv;
return phicoul + philj;
}
/* ---------------------------------------------------------------------- */
void *PairLJSDKCoulMSM::extract(const char *str, int &dim)
{
dim = 2;
if (strcmp(str,"epsilon") == 0) return (void *) epsilon;
if (strcmp(str,"sigma") == 0) return (void *) sigma;
if (strcmp(str,"lj_type") == 0) return (void *) lj_type;
if (strcmp(str,"lj1") == 0) return (void *) lj1;
if (strcmp(str,"lj2") == 0) return (void *) lj2;
if (strcmp(str,"lj3") == 0) return (void *) lj3;
if (strcmp(str,"lj4") == 0) return (void *) lj4;
if (strcmp(str,"rminsq") == 0) return (void *) rminsq;
if (strcmp(str,"emin") == 0) return (void *) emin;
dim = 0;
if (strcmp(str,"cut_coul") == 0) return (void *) &cut_coul;
if (strcmp(str,"cut_msm") == 0) return (void *) &cut_coul;
return NULL;
}

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