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66e885b6e529329ac910725db138f69e9d725b68
lammps/src/USER-YAFF/pair_mm3_switch3_coulgauss_long.cpp
Axel Kohlmeyer 66e885b6e5 Merge branch 'master' into collected-small-changes 
# Conflicts:
#	src/USER-YAFF/pair_lj_switch3_coulgauss_long.cpp
#	src/USER-YAFF/pair_mm3_switch3_coulgauss_long.cpp
2021-04-02 17:57:54 -04:00

680 lines
22 KiB
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/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
https://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: Steven Vandenbrande
------------------------------------------------------------------------- */
#include "pair_mm3_switch3_coulgauss_long.h"
#include "atom.h"
#include "comm.h"
#include "error.h"
#include "force.h"
#include "kspace.h"
#include "math_const.h"
#include "memory.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "update.h"
#include <cmath>
#include <cstring>
using namespace LAMMPS_NS;
using namespace MathConst;
#define EWALD_F 1.12837917
#define EWALD_P 0.3275911
#define A1 0.254829592
#define A2 -0.284496736
#define A3 1.421413741
#define A4 -1.453152027
#define A5 1.061405429
/* ---------------------------------------------------------------------- */
PairMM3Switch3CoulGaussLong::PairMM3Switch3CoulGaussLong(LAMMPS *lmp) : Pair(lmp)
{
ewaldflag = pppmflag = 1;
writedata = 1;
ftable = nullptr;
qdist = 0.0;
}
/* ---------------------------------------------------------------------- */
PairMM3Switch3CoulGaussLong::~PairMM3Switch3CoulGaussLong()
{
if (allocated) {
memory->destroy(setflag);
memory->destroy(cutsq);
memory->destroy(cut_lj);
memory->destroy(cut_ljsq);
memory->destroy(epsilon);
memory->destroy(sigma);
memory->destroy(gamma);
memory->destroy(lj1);
memory->destroy(lj2);
memory->destroy(lj3);
memory->destroy(lj4);
memory->destroy(offset);
}
if (ftable) free_tables();
}
/* ---------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::compute(int eflag, int vflag)
{
int i,ii,j,jj,inum,jnum,itype,jtype,itable;
double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
double fraction,table;
double r,r2inv,r6inv,forcecoul,forcecoul2,forcelj,factor_coul,factor_lj,tr,ftr,trx;
double grij,expm2,prefactor,prefactor2,t,erfc1,erfc2,rrij,expn2,expb;
int *ilist,*jlist,*numneigh,**firstneigh;
double rsq;
evdwl = ecoul = 0.0;
ev_init(eflag,vflag);
double **x = atom->x;
double **f = atom->f;
double *q = atom->q;
int *type = atom->type;
int nlocal = atom->nlocal;
double *special_coul = force->special_coul;
double *special_lj = force->special_lj;
int newton_pair = force->newton_pair;
double qqrd2e = force->qqrd2e;
union_int_float_t rsq_lookup;
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];
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]) {
r2inv = 1.0/rsq;
if (rsq < cut_coulsq) {
if (!ncoultablebits || rsq <= tabinnersq) {
r = sqrt(rsq);
grij = g_ewald * r;
expm2 = exp(-grij*grij);
t = 1.0 / (1.0 + EWALD_P*grij);
erfc1 = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;
prefactor = qqrd2e * qtmp*q[j]/r;
forcecoul = prefactor * (erfc1 + EWALD_F*grij*expm2);
if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;
} else {
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 (factor_coul < 1.0) {
table = ctable[itable] + fraction*dctable[itable];
prefactor = qtmp*q[j] * table;
forcecoul -= (1.0-factor_coul)*prefactor;
}
}
} else forcecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
// Repulsive exponential part
r = sqrt(rsq);
expb = lj3[itype][jtype]*exp(-lj1[itype][jtype]*r);
forcelj = expb*lj1[itype][jtype]*r;
// Attractive r^-6 part
r6inv = r2inv*r2inv*r2inv;
forcelj -= 6.0*lj4[itype][jtype]*r6inv;
// Correction for Gaussian radii
if (lj2[itype][jtype]==0.0) {
// This means a point charge is considered, so the correction is zero
expn2 = 0.0;
erfc2 = 0.0;
forcecoul2 = 0.0;
} else {
rrij = lj2[itype][jtype]*r;
expn2 = exp(-rrij*rrij);
erfc2 = erfc(rrij);
prefactor2 = -qqrd2e*qtmp*q[j]/r;
forcecoul2 = prefactor2*(erfc2+EWALD_F*rrij*expn2);
}
} else forcelj = 0.0;
if (rsq < cut_coulsq) {
if (!ncoultablebits || rsq <= tabinnersq)
ecoul = prefactor*erfc1;
else {
table = etable[itable] + fraction*detable[itable];
ecoul = qtmp*q[j] * table;
}
if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
} else ecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
ecoul += prefactor2*erfc2*factor_coul;
evdwl = expb-lj4[itype][jtype]*r6inv-offset[itype][jtype];
} else evdwl = 0.0;
// Truncation, see Yaff Switch3
if (truncw>0) {
if (rsq < cut_ljsq[itype][jtype]) {
if (r>cut_lj[itype][jtype]-truncw) {
trx = (cut_lj[itype][jtype]-r)*truncwi;
tr = trx*trx*(3.0-2.0*trx);
ftr = 6.0*trx*(1.0-trx)*r*truncwi;
forcelj = forcelj*tr + evdwl*ftr;
evdwl *= tr;
}
}
}
fpair = (forcecoul + factor_coul*forcecoul2 + factor_lj*forcelj) * r2inv;
evdwl *= factor_lj;
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 (evflag) ev_tally(i,j,nlocal,newton_pair,
evdwl,ecoul,fpair,delx,dely,delz);
}
}
}
if (vflag_fdotr) virial_fdotr_compute();
}
/* ----------------------------------------------------------------------
allocate all arrays
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::allocate()
{
allocated = 1;
int n = atom->ntypes;
memory->create(setflag,n+1,n+1,"pair:setflag");
for (int i = 1; i <= n; i++)
for (int j = i; j <= n; j++)
setflag[i][j] = 0;
memory->create(cutsq,n+1,n+1,"pair:cutsq");
memory->create(cut_lj,n+1,n+1,"pair:cut_lj");
memory->create(cut_ljsq,n+1,n+1,"pair:cut_ljsq");
memory->create(epsilon,n+1,n+1,"pair:epsilon");
memory->create(sigma,n+1,n+1,"pair:sigma");
memory->create(gamma,n+1,n+1,"pair:gamma");
memory->create(lj1,n+1,n+1,"pair:lj1");
memory->create(lj2,n+1,n+1,"pair:lj2");
memory->create(lj3,n+1,n+1,"pair:lj3");
memory->create(lj4,n+1,n+1,"pair:lj4");
memory->create(offset,n+1,n+1,"pair:offset");
}
/* ----------------------------------------------------------------------
global settings
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::settings(int narg, char **arg)
{
if (narg < 2 || narg > 3) error->all(FLERR,"Illegal pair_style command");
cut_lj_global = utils::numeric(FLERR,arg[0],false,lmp);
if (narg == 2) {
cut_coul = cut_lj_global;
truncw = utils::numeric(FLERR,arg[1],false,lmp);
}
else {
cut_coul = utils::numeric(FLERR,arg[1],false,lmp);
truncw = utils::numeric(FLERR,arg[2],false,lmp);
}
if (truncw>0.0) truncwi = 1.0/truncw;
else truncwi = 0.0;
// reset cutoffs that have been explicitly set
if (allocated) {
int i,j;
for (i = 1; i <= atom->ntypes; i++)
for (j = i; j <= atom->ntypes; j++)
if (setflag[i][j]) cut_lj[i][j] = cut_lj_global;
}
}
/* ----------------------------------------------------------------------
set coeffs for one or more type pairs
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::coeff(int narg, char **arg)
{
if (narg < 5 || narg > 6)
error->all(FLERR,"Incorrect args for pair coefficients");
if (!allocated) allocate();
int ilo,ihi,jlo,jhi;
utils::bounds(FLERR,arg[0],1,atom->ntypes,ilo,ihi,error);
utils::bounds(FLERR,arg[1],1,atom->ntypes,jlo,jhi,error);
double epsilon_one = utils::numeric(FLERR,arg[2],false,lmp);
double sigma_one = utils::numeric(FLERR,arg[3],false,lmp);
double gamma_one = utils::numeric(FLERR,arg[4],false,lmp);
double cut_lj_one = cut_lj_global;
if (narg == 6) cut_lj_one = utils::numeric(FLERR,arg[5],false,lmp);
int count = 0;
for (int i = ilo; i <= ihi; i++) {
for (int j = MAX(jlo,i); j <= jhi; j++) {
epsilon[i][j] = epsilon_one;
sigma[i][j] = sigma_one;
gamma[i][j] = gamma_one;
cut_lj[i][j] = cut_lj_one;
setflag[i][j] = 1;
count++;
}
}
if (count == 0) error->all(FLERR,"Incorrect args for pair coefficients");
}
/* ----------------------------------------------------------------------
init specific to this pair style
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::init_style()
{
if (!atom->q_flag)
error->all(FLERR,"Pair style mm3/switch3/coulgauss/long requires atom attribute q");
cut_coulsq = cut_coul * cut_coul;
// insure use of KSpace long-range solver, set g_ewald
if (force->kspace == nullptr)
error->all(FLERR,"Pair style requires a KSpace style");
g_ewald = force->kspace->g_ewald;
neighbor->request(this,instance_me);
// setup force tables
if (ncoultablebits) init_tables(cut_coul,nullptr);
}
/* ----------------------------------------------------------------------
init for one type pair i,j and corresponding j,i
------------------------------------------------------------------------- */
double PairMM3Switch3CoulGaussLong::init_one(int i, int j)
{
if (setflag[i][j] == 0) {
epsilon[i][j] = sqrt(epsilon[i][i]*epsilon[j][j]);
sigma[i][j] = 0.5*(sigma[i][i] + sigma[j][j]);
gamma[i][j] = 1.0/sqrt(gamma[i][i]*gamma[i][i]+gamma[j][j]*gamma[j][j]);
cut_lj[i][j] = mix_distance(cut_lj[i][i],cut_lj[j][j]);
}
double cut = MAX(cut_lj[i][j],cut_coul+2.0*qdist);
cut_ljsq[i][j] = cut_lj[i][j] * cut_lj[i][j];
lj1[i][j] = 12.0 / (2.0*sigma[i][j]);
if (gamma[i][i]==0.0 && gamma[j][j]==0.0) lj2[i][j] = 0.0;
else lj2[i][j] = 1.0/sqrt(gamma[i][i]*gamma[i][i]+gamma[j][j]*gamma[j][j]);
lj3[i][j] = 1.84e5 * epsilon[i][j];
lj4[i][j] = 2.25 * epsilon[i][j] * pow(2.0*sigma[i][j],6.0);
if (offset_flag && (cut_lj[i][j] > 0.0)) {
// Truncation is active, so offset is zero, except if truncw==0.0
if (truncw==0.0) {
double r = cut_lj[i][j];
double r2inv = 1.0/(r*r);
double r6inv = r2inv*r2inv*r2inv;
double expb = lj3[i][j]*exp(-lj1[i][j]*r);
offset[i][j] = expb-lj4[i][j]*r6inv;
}
else {offset[i][j] = 0.0;}
} else offset[i][j] = 0.0;
cut_ljsq[j][i] = cut_ljsq[i][j];
cut_lj[j][i] = cut_lj[i][j];
lj1[j][i] = lj1[i][j];
lj2[j][i] = lj2[i][j];
lj3[j][i] = lj3[i][j];
lj4[j][i] = lj4[i][j];
offset[j][i] = offset[i][j];
// compute I,J contribution to long-range tail correction
// count total # of atoms of type I and J via Allreduce
if (tail_flag) {
int *type = atom->type;
int nlocal = atom->nlocal;
double count[2],all[2];
count[0] = count[1] = 0.0;
for (int k = 0; k < nlocal; k++) {
if (type[k] == i) count[0] += 1.0;
if (type[k] == j) count[1] += 1.0;
}
MPI_Allreduce(count,all,2,MPI_DOUBLE,MPI_SUM,world);
double cg = epsilon[i][j];
double cg1 = cut_lj[i][j];
double cg3 = 2.0*sigma[i][j];//Mind the factor 2 here!!!
if (truncw > 0.0) {
double cg5 = truncw;
double t1 = pow(cg3, 0.2e1);
double t2 = t1 * cg3;
double t3 = 0.5e1 / 0.216e3 * t2;
double t5 = cg1 / 0.9e1;
double t8 = -cg1 + cg5;
double t14 = t8 * t8;
double t17 = 0.1e1 / cg3;
double t20 = exp(0.12e2 * t17 * cg5);
double t30 = pow(cg1, 0.2e1);
double t36 = exp(-0.12e2 * t17 * cg1);
double t37 = pow(cg5, 0.2e1);
double t39 = 0.1e1 / t37 / cg5;
double t43 = cg1 * t8;
double t44 = log(-t8);
double t47 = log(cg1);
double t54 = t1 * t1;
double t64 = cg * (0.6388888889e3 * ((-t3 + (0.7e1 / 0.36e2 * cg5 - t5) * t1 - 0.2e1 / 0.3e1 * t8 * (cg5 - cg1 / 0.4e1) * cg3 + cg5 * t14) * t20 + t3 + (cg5 / 0.12e2 + t5) * t1 + (cg5 + cg1 / 0.3e1) * cg1 * cg3 / 0.2e1 + t30 * cg5) * t2 * t36 * t39 - 0.225e1 * (0.2e1 * t43 * t44 - 0.2e1 * t43 * t47 + cg5 * (cg5 - 0.2e1 * cg1)) * t54 * t1 / cg1 / t8 * t39);
etail_ij = 2.0*MY_PI*all[0]*all[1]*t64;
ptail_ij = 2.0*MY_PI*all[0]*all[1]*t64;
}
else {
double t2 = pow(cg3, 0.2e1);
double t3 = t2 * t2;
double t7 = 0.12e2 / cg3 * cg1;
double t8 = exp(t7);
double t11 = pow(cg1, 0.2e1);
double t12 = t11 * t11;
double t17 = t11 * cg1;
double t21 = exp(-t7);
double t27 = -0.9259259259e-2 * cg3 * cg * (0.81e2 * t3 * cg3 * t8 - 0.1656000e7 * t12 * cg1 - 0.276000e6 * cg3 * t12 - 0.23000e5 * t2 * t17) * t21 / t17;
double t1 = pow(cg3, 0.2e1);
t2 = t1 * t1;
double t6 = 0.12e2 / cg3 * cg1;
t7 = exp(t6);
double t10 = pow(cg1, 0.2e1);
t11 = t10 * t10;
double t19 = t10 * cg1;
double t25 = exp(-t6);
double t29 = 0.5555555556e-1 * cg * (0.81e2 * t2 * t1 * t7 - 0.3312000e7 * t11 * t10 - 0.828000e6 * cg3 * t11 * cg1 - 0.138000e6 * t1 * t11 - 0.11500e5 * t19 * t1 * cg3) * t25 / t19;
etail_ij = 2.0*MY_PI*all[0]*all[1]*t27;
ptail_ij = -2.0/3.0*MY_PI*all[0]*all[1]*t29;
}
}
return cut;
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::write_restart(FILE *fp)
{
write_restart_settings(fp);
int i,j;
for (i = 1; i <= atom->ntypes; i++)
for (j = i; j <= atom->ntypes; j++) {
fwrite(&setflag[i][j],sizeof(int),1,fp);
if (setflag[i][j]) {
fwrite(&epsilon[i][j],sizeof(double),1,fp);
fwrite(&sigma[i][j],sizeof(double),1,fp);
fwrite(&gamma[i][j],sizeof(double),1,fp);
fwrite(&cut_lj[i][j],sizeof(double),1,fp);
}
}
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::read_restart(FILE *fp)
{
read_restart_settings(fp);
allocate();
int i,j;
int me = comm->me;
for (i = 1; i <= atom->ntypes; i++)
for (j = i; j <= atom->ntypes; j++) {
if (me == 0) utils::sfread(FLERR,&setflag[i][j],sizeof(int),1,fp,nullptr,error);
MPI_Bcast(&setflag[i][j],1,MPI_INT,0,world);
if (setflag[i][j]) {
if (me == 0) {
utils::sfread(FLERR,&epsilon[i][j],sizeof(double),1,fp,nullptr,error);
utils::sfread(FLERR,&sigma[i][j],sizeof(double),1,fp,nullptr,error);
utils::sfread(FLERR,&gamma[i][j],sizeof(double),1,fp,nullptr,error);
utils::sfread(FLERR,&cut_lj[i][j],sizeof(double),1,fp,nullptr,error);
}
MPI_Bcast(&epsilon[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&sigma[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&gamma[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_lj[i][j],1,MPI_DOUBLE,0,world);
}
}
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::write_restart_settings(FILE *fp)
{
fwrite(&cut_lj_global,sizeof(double),1,fp);
fwrite(&cut_coul,sizeof(double),1,fp);
fwrite(&truncw,sizeof(double),1,fp);
fwrite(&offset_flag,sizeof(int),1,fp);
fwrite(&mix_flag,sizeof(int),1,fp);
fwrite(&tail_flag,sizeof(int),1,fp);
fwrite(&ncoultablebits,sizeof(int),1,fp);
fwrite(&tabinner,sizeof(double),1,fp);
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::read_restart_settings(FILE *fp)
{
if (comm->me == 0) {
utils::sfread(FLERR,&cut_lj_global,sizeof(double),1,fp,nullptr,error);
utils::sfread(FLERR,&cut_coul,sizeof(double),1,fp,nullptr,error);
utils::sfread(FLERR,&truncw,sizeof(double),1,fp,nullptr,error);
utils::sfread(FLERR,&offset_flag,sizeof(int),1,fp,nullptr,error);
utils::sfread(FLERR,&mix_flag,sizeof(int),1,fp,nullptr,error);
utils::sfread(FLERR,&tail_flag,sizeof(int),1,fp,nullptr,error);
utils::sfread(FLERR,&ncoultablebits,sizeof(int),1,fp,nullptr,error);
utils::sfread(FLERR,&tabinner,sizeof(double),1,fp,nullptr,error);
}
MPI_Bcast(&cut_lj_global,1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_coul,1,MPI_DOUBLE,0,world);
MPI_Bcast(&truncw,1,MPI_DOUBLE,0,world);
MPI_Bcast(&offset_flag,1,MPI_INT,0,world);
MPI_Bcast(&mix_flag,1,MPI_INT,0,world);
MPI_Bcast(&tail_flag,1,MPI_INT,0,world);
MPI_Bcast(&ncoultablebits,1,MPI_INT,0,world);
MPI_Bcast(&tabinner,1,MPI_DOUBLE,0,world);
}
/* ----------------------------------------------------------------------
proc 0 writes to data file
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::write_data(FILE *fp)
{
for (int i = 1; i <= atom->ntypes; i++)
fprintf(fp,"%d %g %g %g\n",i,epsilon[i][i],sigma[i][i],gamma[i][i]);
}
/* ----------------------------------------------------------------------
proc 0 writes all pairs to data file
------------------------------------------------------------------------- */
void PairMM3Switch3CoulGaussLong::write_data_all(FILE *fp)
{
for (int i = 1; i <= atom->ntypes; i++)
for (int j = i; j <= atom->ntypes; j++)
fprintf(fp,"%d %d %g %g %g %g\n",i,j,epsilon[i][j],sigma[i][j],gamma[i][j],cut_lj[i][j]);
}
/* ---------------------------------------------------------------------- */
double PairMM3Switch3CoulGaussLong::single(int i, int j, int itype, int jtype,
double rsq,
double factor_coul, double factor_lj,
double &fforce)
{
double r2inv,r6inv,r,grij,expm2,t,erfc1,prefactor,prefactor2;
double fraction,table,forcecoul,forcecoul2,forcelj;
double expb,rrij,expn2,erfc2,evdwl,ecoul,trx,tr,ftr;
int itable;
r2inv = 1.0/rsq;
if (rsq < cut_coulsq) {
if (!ncoultablebits || rsq <= tabinnersq) {
r = sqrt(rsq);
grij = g_ewald * r;
expm2 = exp(-grij*grij);
t = 1.0 / (1.0 + EWALD_P*grij);
erfc1 = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;
prefactor = force->qqrd2e * atom->q[i]*atom->q[j]/r;
forcecoul = prefactor * (erfc1 + EWALD_F*grij*expm2);
if (factor_coul < 1.0) forcecoul -= (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;
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;
}
}
} else forcecoul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) {
r = sqrt(rsq);
expb = lj3[itype][jtype]*exp(-lj1[itype][jtype]*r);
forcelj = expb*lj1[itype][jtype]*r;
r6inv = r2inv*r2inv*r2inv;
forcelj -= 6.0*lj4[itype][jtype]*r6inv;
if (lj2[itype][jtype] == 0.0) {
expn2 = 0.0;
erfc2 = 0.0;
forcecoul2 = 0.0;
prefactor2 = 0.0;
} else {
rrij = lj2[itype][jtype]*r;
expn2 = exp(-rrij*rrij);
erfc2 = erfc(rrij);
prefactor2 = -force->qqrd2e * atom->q[i]*atom->q[j]/r;
forcecoul2 = prefactor2 * (erfc2 + EWALD_F*rrij*expn2);
}
} else expb = forcelj = 0.0;
evdwl = ecoul = 0.0;
if (rsq < cut_coulsq) {
if (!ncoultablebits || rsq <= tabinnersq)
ecoul = prefactor*erfc1;
else {
table = etable[itable] + fraction*detable[itable];
ecoul = atom->q[i]*atom->q[j] * table;
}
if (factor_coul < 1.0) ecoul -= (1.0-factor_coul)*prefactor;
}
if (rsq < cut_ljsq[itype][jtype]) {
ecoul += prefactor2*erfc2*factor_coul;
evdwl = expb-lj4[itype][jtype]*r6inv-offset[itype][jtype];
} else evdwl = 0.0;
// Truncation, see Yaff Switch3
if (truncw > 0) {
if (rsq < cut_ljsq[itype][jtype]) {
if (r>cut_lj[itype][jtype]-truncw) {
trx = (cut_lj[itype][jtype]-r)*truncwi;
tr = trx*trx*(3.0-2.0*trx);
ftr = 6.0*trx*(1.0-trx)*r*truncwi;
forcelj = forcelj*tr + evdwl*ftr;
evdwl *= tr;
}
}
}
fforce = (forcecoul + factor_coul*forcecoul2 + factor_lj*forcelj) * r2inv;
return ecoul + evdwl*factor_lj;
;
}
/* ---------------------------------------------------------------------- */
void *PairMM3Switch3CoulGaussLong::extract(const char *str, int &dim)
{
dim = 0;
if (strcmp(str,"cut_coul") == 0) return (void *) &cut_coul;
dim = 2;
if (strcmp(str,"epsilon") == 0) return (void *) epsilon;
if (strcmp(str,"sigma") == 0) return (void *) sigma;
if (strcmp(str,"gamma") == 0) return (void *) gamma;
return nullptr;
}
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