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Adding coulomb tabling. 

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@9055 f3b2605a-c512-4ea7-a41b-209d697bcdaa
This commit is contained in:
pscrozi 2012-11-12 20:43:13 +00:00
parent 9d084fc662
commit cc101e578a
1 changed files with 73 additions and 21 deletions
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94
src/CLASS2/pair_lj_class2_coul_long.cpp
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@ -42,6 +42,7 @@ using namespace MathConst;
PairLJClass2CoulLong::PairLJClass2CoulLong(LAMMPS *lmp) : Pair(lmp)
{
ewaldflag = pppmflag = 1;
ftable = NULL;
}
/* ---------------------------------------------------------------------- */
@ -68,8 +69,9 @@ PairLJClass2CoulLong::~PairLJClass2CoulLong()
void PairLJClass2CoulLong::compute(int eflag, int vflag)
{
int i,j,ii,jj,inum,jnum,itype,jtype;
int i,j,ii,jj,inum,jnum,itable,itype,jtype;
double qtmp,xtmp,ytmp,ztmp,delx,dely,delz,evdwl,ecoul,fpair;
double fraction,table;
double rsq,r,rinv,r2inv,r3inv,r6inv,forcecoul,forcelj;
double grij,expm2,prefactor,t,erfc;
double factor_coul,factor_lj;
@ -122,14 +124,29 @@ void PairLJClass2CoulLong::compute(int eflag, int vflag)
r2inv = 1.0/rsq;
if (rsq < cut_coulsq) {
r = sqrt(rsq);
grij = g_ewald * r;
expm2 = exp(-grij*grij);
t = 1.0 / (1.0 + EWALD_P*grij);
erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;
prefactor = qqrd2e * qtmp*q[j]/r;
forcecoul = prefactor * (erfc + EWALD_F*grij*expm2);
if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;
if (!ncoultablebits || rsq <= tabinnersq) {
r = sqrt(rsq);
grij = g_ewald * r;
expm2 = exp(-grij*grij);
t = 1.0 / (1.0 + EWALD_P*grij);
erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;
prefactor = qqrd2e * qtmp*q[j]/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 = 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]) {
@ -152,7 +169,12 @@ void PairLJClass2CoulLong::compute(int eflag, int vflag)
if (eflag) {
if (rsq < cut_coulsq) {
ecoul = prefactor*erfc;
if (!ncoultablebits || rsq <= tabinnersq)
ecoul = prefactor*erfc;
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]) {
@ -270,9 +292,12 @@ void PairLJClass2CoulLong::init_style()
// insure use of KSpace long-range solver, set g_ewald
if (force->kspace == NULL)
if (force->kspace == NULL)
error->all(FLERR,"Pair style requires a KSpace style");
g_ewald = force->kspace->g_ewald;
// setup force tables
if (ncoultablebits) init_tables(cut_coul,NULL);
}
/* ----------------------------------------------------------------------
@ -400,6 +425,8 @@ void PairLJClass2CoulLong::write_restart_settings(FILE *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);
}
/* ----------------------------------------------------------------------
@ -414,12 +441,16 @@ void PairLJClass2CoulLong::read_restart_settings(FILE *fp)
fread(&offset_flag,sizeof(int),1,fp);
fread(&mix_flag,sizeof(int),1,fp);
fread(&tail_flag,sizeof(int),1,fp);
fread(&ncoultablebits,sizeof(int),1,fp);
fread(&tabinner,sizeof(double),1,fp);
}
MPI_Bcast(&cut_lj_global,1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_coul,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);
}
/* ---------------------------------------------------------------------- */
@ -430,18 +461,34 @@ double PairLJClass2CoulLong::single(int i, int j, int itype, int jtype,
double &fforce)
{
double r2inv,r,rinv,r3inv,r6inv,grij,expm2,t,erfc,prefactor;
double forcecoul,forcelj,phicoul,philj;
double fraction,table,forcecoul,forcelj,phicoul,philj;
int itable;
r2inv = 1.0/rsq;
if (rsq < cut_coulsq) {
r = sqrt(rsq);
grij = g_ewald * r;
expm2 = exp(-grij*grij);
t = 1.0 / (1.0 + EWALD_P*grij);
erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;
prefactor = force->qqrd2e * atom->q[i]*atom->q[j]/r;
forcecoul = prefactor * (erfc + EWALD_F*grij*expm2);
if (factor_coul < 1.0) forcecoul -= (1.0-factor_coul)*prefactor;
if (!ncoultablebits || rsq <= tabinnersq) {
r = sqrt(rsq);
grij = g_ewald * r;
expm2 = exp(-grij*grij);
t = 1.0 / (1.0 + EWALD_P*grij);
erfc = t * (A1+t*(A2+t*(A3+t*(A4+t*A5)))) * expm2;
prefactor = force->qqrd2e * atom->q[i]*atom->q[j]/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 = 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]) {
rinv = sqrt(r2inv);
@ -453,7 +500,12 @@ double PairLJClass2CoulLong::single(int i, int j, int itype, int jtype,
double eng = 0.0;
if (rsq < cut_coulsq) {
phicoul = prefactor*erfc;
if (!ncoultablebits || rsq <= tabinnersq)
phicoul = prefactor*erfc;
else {
table = etable[itable] + fraction*detable[itable];
phicoul = atom->q[i]*atom->q[j] * table;
}
if (factor_coul < 1.0) phicoul -= (1.0-factor_coul)*prefactor;
eng += phicoul;
}