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pair_buck_disp_coul_long.cpp
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Fri, Nov 15, 05:11

pair_buck_disp_coul_long.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: Pieter J. in 't Veld (SNL)
------------------------------------------------------------------------- */
#include "math.h"
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "math_vector.h"
#include "pair_buck_disp_coul_long.h"
#include "atom.h"
#include "comm.h"
#include "neighbor.h"
#include "neigh_list.h"
#include "neigh_request.h"
#include "force.h"
#include "kspace.h"
#include "update.h"
#include "integrate.h"
#include "respa.h"
#include "memory.h"
#include "error.h"
using namespace LAMMPS_NS;
#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
/* ---------------------------------------------------------------------- */
PairBuckDispCoulLong::PairBuckDispCoulLong(LAMMPS *lmp) : Pair(lmp)
{
dispersionflag = ewaldflag = pppmflag = 1;
respa_enable = 1;
ftable = NULL;
}
/* ----------------------------------------------------------------------
global settings
------------------------------------------------------------------------- */
#define PAIR_ILLEGAL "Illegal pair_style buck/coul command"
#define PAIR_CUTOFF "Only one cut-off allowed when requesting all long"
#define PAIR_MISSING "Cut-offs missing in pair_style buck/coul"
#define PAIR_LJ_OFF "LJ6 off not supported in pair_style buck/coul"
#define PAIR_COUL_CUT "Coulombic cut not supported in pair_style buck/coul"
#define PAIR_LARGEST "Using largest cut-off for buck/coul long long"
#define PAIR_MIX "Geometric mixing assumed for 1/r^6 coefficients"
void PairBuckDispCoulLong::options(char **arg, int order)
{
const char *option[] = {"long", "cut", "off", NULL};
int i;
if (!*arg) error->all(FLERR,PAIR_ILLEGAL);
for (i=0; option[i]&&strcmp(arg[0], option[i]); ++i);
switch (i) {
default: error->all(FLERR,PAIR_ILLEGAL);
case 0: ewald_order |= 1<<order; break;
case 2: ewald_off |= 1<<order;
case 1: break;
}
}
/* ---------------------------------------------------------------------- */
void PairBuckDispCoulLong::settings(int narg, char **arg)
{
if (narg != 3 && narg != 4) error->all(FLERR,"Illegal pair_style command");
ewald_order = 0;
ewald_off = 0;
options(arg, 6);
options(++arg, 1);
if (!comm->me && ewald_order&(1<<6)) error->warning(FLERR,PAIR_MIX);
if (!comm->me && ewald_order==((1<<1)|(1<<6)))
error->warning(FLERR,PAIR_LARGEST);
if (!*(++arg)) error->all(FLERR,PAIR_MISSING);
if (ewald_off&(1<<6)) error->all(FLERR,PAIR_LJ_OFF);
if (!((ewald_order^ewald_off)&(1<<1))) error->all(FLERR,PAIR_COUL_CUT);
cut_buck_global = force->numeric(*(arg++));
if (*arg&&(ewald_order&0x42==0x42)) error->all(FLERR,PAIR_CUTOFF);
if (narg == 4) cut_coul = force->numeric(*arg);
else cut_coul = cut_buck_global;
if (allocated) {
int i,j;
for (i = 1; i <= atom->ntypes; i++)
for (j = i+1; j <= atom->ntypes; j++)
if (setflag[i][j]) cut_buck[i][j] = cut_buck_global;
}
}
/* ----------------------------------------------------------------------
free all arrays
------------------------------------------------------------------------- */
PairBuckDispCoulLong::~PairBuckDispCoulLong()
{
if (allocated) {
memory->destroy(setflag);
memory->destroy(cutsq);
memory->destroy(cut_buck_read);
memory->destroy(cut_buck);
memory->destroy(cut_bucksq);
memory->destroy(buck_a_read);
memory->destroy(buck_a);
memory->destroy(buck_c_read);
memory->destroy(buck_c);
memory->destroy(buck_rho_read);
memory->destroy(buck_rho);
memory->destroy(buck1);
memory->destroy(buck2);
memory->destroy(rhoinv);
memory->destroy(offset);
}
if (ftable) free_tables();
}
/* ----------------------------------------------------------------------
allocate all arrays
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::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_buck_read,n+1,n+1,"pair:cut_buck_read");
memory->create(cut_buck,n+1,n+1,"pair:cut_buck");
memory->create(cut_bucksq,n+1,n+1,"pair:cut_bucksq");
memory->create(buck_a_read,n+1,n+1,"pair:buck_a_read");
memory->create(buck_a,n+1,n+1,"pair:buck_a");
memory->create(buck_c_read,n+1,n+1,"pair:buck_c_read");
memory->create(buck_c,n+1,n+1,"pair:buck_c");
memory->create(buck_rho_read,n+1,n+1,"pair:buck_rho_read");
memory->create(buck_rho,n+1,n+1,"pair:buck_rho");
memory->create(buck1,n+1,n+1,"pair:buck1");
memory->create(buck2,n+1,n+1,"pair:buck2");
memory->create(rhoinv,n+1,n+1,"pair:rhoinv");
memory->create(offset,n+1,n+1,"pair:offset");
}
/* ----------------------------------------------------------------------
extract protected data from object
------------------------------------------------------------------------- */
void *PairBuckDispCoulLong::extract(const char *id, int &dim)
{
const char *ids[] = {
"B", "ewald_order", "ewald_cut", "ewald_mix", "cut_coul", "cut_LJ", NULL};
void *ptrs[] = {
buck_c, &ewald_order, &cut_coul, &mix_flag, &cut_coul, &cut_buck_global,
NULL};
int i;
for (i=0; ids[i]&&strcmp(ids[i], id); ++i);
if (i == 0) dim = 2;
else dim = 0;
return ptrs[i];
}
/* ----------------------------------------------------------------------
set coeffs for one or more type pairs
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::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;
force->bounds(*(arg++),atom->ntypes,ilo,ihi);
force->bounds(*(arg++),atom->ntypes,jlo,jhi);
double buck_a_one = force->numeric(*(arg++));
double buck_rho_one = force->numeric(*(arg++));
double buck_c_one = force->numeric(*(arg++));
double cut_buck_one = cut_buck_global;
if (narg == 6) cut_buck_one = force->numeric(*(arg++));
int count = 0;
for (int i = ilo; i <= ihi; i++) {
for (int j = MAX(jlo,i); j <= jhi; j++) {
buck_a_read[i][j] = buck_a_one;
buck_c_read[i][j] = buck_c_one;
buck_rho_read[i][j] = buck_rho_one;
cut_buck_read[i][j] = cut_buck_one;
setflag[i][j] = 1;
count++;
}
}
if (count == 0) error->all(FLERR,"Incorrect args for pair coefficients");
}
/* ----------------------------------------------------------------------
init specific to this pair style
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::init_style()
{
// require an atom style with charge defined
if (!atom->q_flag && (ewald_order&(1<<1)))
error->all(FLERR,
"Invoking coulombic in pair style lj/coul requires atom attribute q");
// request regular or rRESPA neighbor lists
int irequest;
if (update->whichflag == 0 && strstr(update->integrate_style,"respa")) {
int respa = 0;
if (((Respa *) update->integrate)->level_inner >= 0) respa = 1;
if (((Respa *) update->integrate)->level_middle >= 0) respa = 2;
if (respa == 0) irequest = neighbor->request(this);
else if (respa == 1) {
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 1;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respainner = 1;
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 3;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respaouter = 1;
} else {
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 1;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respainner = 1;
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 2;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respamiddle = 1;
irequest = neighbor->request(this);
neighbor->requests[irequest]->id = 3;
neighbor->requests[irequest]->half = 0;
neighbor->requests[irequest]->respaouter = 1;
}
} else irequest = neighbor->request(this);
cut_coulsq = cut_coul * cut_coul;
// set rRESPA cutoffs
if (strstr(update->integrate_style,"respa") &&
((Respa *) update->integrate)->level_inner >= 0)
cut_respa = ((Respa *) update->integrate)->cutoff;
else cut_respa = NULL;
// ensure use of KSpace long-range solver, set two g_ewalds
if (force->kspace == NULL)
error->all(FLERR,"Pair style requires a KSpace style");
if (ewald_order&(1<<1)) g_ewald = force->kspace->g_ewald;
if (ewald_order&(1<<6)) g_ewald_6 = force->kspace->g_ewald_6;
// setup force tables
if (ncoultablebits) init_tables();
}
/* ----------------------------------------------------------------------
neighbor callback to inform pair style of neighbor list to use
regular or rRESPA
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::init_list(int id, NeighList *ptr)
{
if (id == 0) list = ptr;
else if (id == 1) listinner = ptr;
else if (id == 2) listmiddle = ptr;
else if (id == 3) listouter = ptr;
}
/* ----------------------------------------------------------------------
init for one type pair i,j and corresponding j,i
------------------------------------------------------------------------- */
double PairBuckDispCoulLong::init_one(int i, int j)
{
if (setflag[i][j] == 0) error->all(FLERR,"All pair coeffs are not set");
cut_buck[i][j] = cut_buck_read[i][j];
buck_a[i][j] = buck_a_read[i][j];
buck_c[i][j] = buck_c_read[i][j];
buck_rho[i][j] = buck_rho_read[i][j];
double cut = MAX(cut_buck[i][j],cut_coul);
cutsq[i][j] = cut*cut;
cut_bucksq[i][j] = cut_buck[i][j] * cut_buck[i][j];
buck1[i][j] = buck_a[i][j]/buck_rho[i][j];
buck2[i][j] = 6.0*buck_c[i][j];
rhoinv[i][j] = 1.0/buck_rho[i][j];
// check interior rRESPA cutoff
if (cut_respa && MIN(cut_buck[i][j],cut_coul) < cut_respa[3])
error->all(FLERR,"Pair cutoff < Respa interior cutoff");
if (offset_flag) {
double rexp = exp(-cut_buck[i][j]/buck_rho[i][j]);
offset[i][j] = buck_a[i][j]*rexp - buck_c[i][j]/pow(cut_buck[i][j],6.0);
} else offset[i][j] = 0.0;
cutsq[j][i] = cutsq[i][j];
cut_bucksq[j][i] = cut_bucksq[i][j];
buck_a[j][i] = buck_a[i][j];
buck_c[j][i] = buck_c[i][j];
rhoinv[j][i] = rhoinv[i][j];
buck1[j][i] = buck1[i][j];
buck2[j][i] = buck2[i][j];
offset[j][i] = offset[i][j];
return cut;
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::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(&buck_a_read[i][j],sizeof(double),1,fp);
fwrite(&buck_rho_read[i][j],sizeof(double),1,fp);
fwrite(&buck_c_read[i][j],sizeof(double),1,fp);
fwrite(&cut_buck_read[i][j],sizeof(double),1,fp);
}
}
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::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) fread(&setflag[i][j],sizeof(int),1,fp);
MPI_Bcast(&setflag[i][j],1,MPI_INT,0,world);
if (setflag[i][j]) {
if (me == 0) {
fread(&buck_a_read[i][j],sizeof(double),1,fp);
fread(&buck_rho_read[i][j],sizeof(double),1,fp);
fread(&buck_c_read[i][j],sizeof(double),1,fp);
fread(&cut_buck_read[i][j],sizeof(double),1,fp);
}
MPI_Bcast(&buck_a_read[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&buck_rho_read[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&buck_c_read[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_buck_read[i][j],1,MPI_DOUBLE,0,world);
}
}
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::write_restart_settings(FILE *fp)
{
fwrite(&cut_buck_global,sizeof(double),1,fp);
fwrite(&cut_coul,sizeof(double),1,fp);
fwrite(&offset_flag,sizeof(int),1,fp);
fwrite(&mix_flag,sizeof(int),1,fp);
fwrite(&ewald_order,sizeof(int),1,fp);
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::read_restart_settings(FILE *fp)
{
if (comm->me == 0) {
fread(&cut_buck_global,sizeof(double),1,fp);
fread(&cut_coul,sizeof(double),1,fp);
fread(&offset_flag,sizeof(int),1,fp);
fread(&mix_flag,sizeof(int),1,fp);
fread(&ewald_order,sizeof(int),1,fp);
}
MPI_Bcast(&cut_buck_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(&ewald_order,1,MPI_INT,0,world);
}
/* ----------------------------------------------------------------------
compute pair interactions
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::compute(int eflag, int vflag)
{
double evdwl,ecoul,fpair;
evdwl = ecoul = 0.0;
if (eflag || vflag) ev_setup(eflag,vflag);
else evflag = vflag_fdotr = 0;
double **x = atom->x, *x0 = x[0];
double **f = atom->f, *f0 = f[0], *fi = f0;
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;
int i, j, order1 = ewald_order&(1<<1), order6 = ewald_order&(1<<6);
int *ineigh, *ineighn, *jneigh, *jneighn, typei, typej, ni;
double qi = 0.0, qri = 0.0, *cutsqi, *cut_bucksqi,
*buck1i, *buck2i, *buckai, *buckci, *rhoinvi, *offseti;
double r, rsq, r2inv, force_coul, force_buck;
double g2 = g_ewald_6*g_ewald_6, g6 = g2*g2*g2, g8 = g6*g2;
vector xi, d;
ineighn = (ineigh = list->ilist)+list->inum;
for (; ineigh<ineighn; ++ineigh) { // loop over my atoms
i = *ineigh; fi = f0+3*i;
if (order1) qri = (qi = q[i])*qqrd2e; // initialize constants
offseti = offset[typei = type[i]];
buck1i = buck1[typei]; buck2i = buck2[typei];
buckai = buck_a[typei]; buckci = buck_c[typei], rhoinvi = rhoinv[typei];
cutsqi = cutsq[typei]; cut_bucksqi = cut_bucksq[typei];
memcpy(xi, x0+(i+(i<<1)), sizeof(vector));
jneighn = (jneigh = list->firstneigh[i])+list->numneigh[i];
for (; jneigh<jneighn; ++jneigh) { // loop over neighbors
j = *jneigh;
ni = sbmask(j);
j &= NEIGHMASK;
{ register double *xj = x0+(j+(j<<1));
d[0] = xi[0] - xj[0]; // pair vector
d[1] = xi[1] - xj[1];
d[2] = xi[2] - xj[2]; }
if ((rsq = vec_dot(d, d)) >= cutsqi[typej = type[j]]) continue;
r2inv = 1.0/rsq;
r = sqrt(rsq);
if (order1 && (rsq < cut_coulsq)) { // coulombic
if (!ncoultablebits || rsq <= tabinnersq) { // series real space
register double x = g_ewald*r;
register double s = qri*q[j], t = 1.0/(1.0+EWALD_P*x);
if (ni == 0) {
s *= g_ewald*exp(-x*x);
force_coul = (t *= ((((t*A5+A4)*t+A3)*t+A2)*t+A1)*s/x)+EWALD_F*s;
if (eflag) ecoul = t;
}
else { // special case
register double f = s*(1.0-special_coul[ni])/r;
s *= g_ewald*exp(-x*x);
force_coul = (t *= ((((t*A5+A4)*t+A3)*t+A2)*t+A1)*s/x)+EWALD_F*s-f;
if (eflag) ecoul = t-f;
}
} // table real space
else {
register union_int_float_t t;
t.f = rsq;
register const int k = (t.i & ncoulmask) >> ncoulshiftbits;
register double f = (rsq-rtable[k])*drtable[k], qiqj = qi*q[j];
if (ni == 0) {
force_coul = qiqj*(ftable[k]+f*dftable[k]);
if (eflag) ecoul = qiqj*(etable[k]+f*detable[k]);
}
else { // special case
t.f = (1.0-special_coul[ni])*(ctable[k]+f*dctable[k]);
force_coul = qiqj*(ftable[k]+f*dftable[k]-t.f);
if (eflag) ecoul = qiqj*(etable[k]+f*detable[k]-t.f);
}
}
}
else force_coul = ecoul = 0.0;
if (rsq < cut_bucksqi[typej]) { // buckingham
register double rn = r2inv*r2inv*r2inv,
expr = exp(-r*rhoinvi[typej]);
if (order6) { // long-range
register double x2 = g2*rsq, a2 = 1.0/x2;
x2 = a2*exp(-x2)*buckci[typej];
if (ni == 0) {
force_buck =
r*expr*buck1i[typej]-g8*(((6.0*a2+6.0)*a2+3.0)*a2+1.0)*x2*rsq;
if (eflag) evdwl = expr*buckai[typej]-g6*((a2+1.0)*a2+0.5)*x2;
}
else { // special case
register double f = special_lj[ni], t = rn*(1.0-f);
force_buck = f*r*expr*buck1i[typej]-
g8*(((6.0*a2+6.0)*a2+3.0)*a2+1.0)*x2*rsq+t*buck2i[typej];
if (eflag) evdwl = f*expr*buckai[typej] -
g6*((a2+1.0)*a2+0.5)*x2+t*buckci[typej];
}
}
else { // cut
if (ni == 0) {
force_buck = r*expr*buck1i[typej]-rn*buck2i[typej];
if (eflag) evdwl = expr*buckai[typej] -
rn*buckci[typej]-offseti[typej];
}
else { // special case
register double f = special_lj[ni];
force_buck = f*(r*expr*buck1i[typej]-rn*buck2i[typej]);
if (eflag)
evdwl = f*(expr*buckai[typej]-rn*buckci[typej]-offseti[typej]);
}
}
}
else force_buck = evdwl = 0.0;
fpair = (force_coul+force_buck)*r2inv;
if (newton_pair || j < nlocal) {
register double *fj = f0+(j+(j<<1)), f;
fi[0] += f = d[0]*fpair; fj[0] -= f;
fi[1] += f = d[1]*fpair; fj[1] -= f;
fi[2] += f = d[2]*fpair; fj[2] -= f;
}
else {
fi[0] += d[0]*fpair;
fi[1] += d[1]*fpair;
fi[2] += d[2]*fpair;
}
if (evflag) ev_tally(i,j,nlocal,newton_pair,
evdwl,ecoul,fpair,d[0],d[1],d[2]);
}
}
if (vflag_fdotr) virial_fdotr_compute();
}
/* ---------------------------------------------------------------------- */
void PairBuckDispCoulLong::compute_inner()
{
double r, rsq, r2inv, force_coul = 0.0, force_buck, fpair;
int *type = atom->type;
int nlocal = atom->nlocal;
double *x0 = atom->x[0], *f0 = atom->f[0], *fi = f0, *q = atom->q;
double *special_coul = force->special_coul;
double *special_lj = force->special_lj;
int newton_pair = force->newton_pair;
double qqrd2e = force->qqrd2e;
double cut_out_on = cut_respa[0];
double cut_out_off = cut_respa[1];
double cut_out_diff = cut_out_off - cut_out_on;
double cut_out_on_sq = cut_out_on*cut_out_on;
double cut_out_off_sq = cut_out_off*cut_out_off;
int *ineigh, *ineighn, *jneigh, *jneighn, typei, typej, ni;
int i, j, order1 = (ewald_order|(ewald_off^-1))&(1<<1);
double qri, *cut_bucksqi, *buck1i, *buck2i, *rhoinvi;
vector xi, d;
ineighn = (ineigh = listinner->ilist)+listinner->inum;
for (; ineigh<ineighn; ++ineigh) { // loop over my atoms
i = *ineigh; fi = f0+3*i;
qri = qqrd2e*q[i];
memcpy(xi, x0+(i+(i<<1)), sizeof(vector));
cut_bucksqi = cut_bucksq[typei = type[i]];
buck1i = buck1[typei]; buck2i = buck2[typei]; rhoinvi = rhoinv[typei];
jneighn = (jneigh = listinner->firstneigh[i])+listinner->numneigh[i];
for (; jneigh<jneighn; ++jneigh) { // loop over neighbors
j = *jneigh;
ni = sbmask(j);
j &= NEIGHMASK;
{ register double *xj = x0+(j+(j<<1));
d[0] = xi[0] - xj[0]; // pair vector
d[1] = xi[1] - xj[1];
d[2] = xi[2] - xj[2]; }
if ((rsq = vec_dot(d, d)) >= cut_out_off_sq) continue;
r2inv = 1.0/rsq;
r = sqrt(rsq);
if (order1 && (rsq < cut_coulsq)) // coulombic
force_coul = ni == 0 ?
qri*q[j]/r : qri*q[j]/r*special_coul[ni];
if (rsq < cut_bucksqi[typej = type[j]]) { // buckingham
register double rn = r2inv*r2inv*r2inv,
expr = exp(-r*rhoinvi[typej]);
force_buck = ni == 0 ?
(r*expr*buck1i[typej]-rn*buck2i[typej]) :
(r*expr*buck1i[typej]-rn*buck2i[typej])*special_lj[ni];
}
else force_buck = 0.0;
fpair = (force_coul + force_buck) * r2inv;
if (rsq > cut_out_on_sq) { // switching
register double rsw = (sqrt(rsq) - cut_out_on)/cut_out_diff;
fpair *= 1.0 + rsw*rsw*(2.0*rsw-3.0);
}
if (newton_pair || j < nlocal) { // force update
register double *fj = f0+(j+(j<<1)), f;
fi[0] += f = d[0]*fpair; fj[0] -= f;
fi[1] += f = d[1]*fpair; fj[1] -= f;
fi[2] += f = d[2]*fpair; fj[2] -= f;
}
else {
fi[0] += d[0]*fpair;
fi[1] += d[1]*fpair;
fi[2] += d[2]*fpair;
}
}
}
}
/* ---------------------------------------------------------------------- */
void PairBuckDispCoulLong::compute_middle()
{
double r, rsq, r2inv, force_coul = 0.0, force_buck, fpair;
int *type = atom->type;
int nlocal = atom->nlocal;
double *x0 = atom->x[0], *f0 = atom->f[0], *fi = f0, *q = atom->q;
double *special_coul = force->special_coul;
double *special_lj = force->special_lj;
int newton_pair = force->newton_pair;
double qqrd2e = force->qqrd2e;
double cut_in_off = cut_respa[0];
double cut_in_on = cut_respa[1];
double cut_out_on = cut_respa[2];
double cut_out_off = cut_respa[3];
double cut_in_diff = cut_in_on - cut_in_off;
double cut_out_diff = cut_out_off - cut_out_on;
double cut_in_off_sq = cut_in_off*cut_in_off;
double cut_in_on_sq = cut_in_on*cut_in_on;
double cut_out_on_sq = cut_out_on*cut_out_on;
double cut_out_off_sq = cut_out_off*cut_out_off;
int *ineigh, *ineighn, *jneigh, *jneighn, typei, typej, ni;
int i, j, order1 = (ewald_order|(ewald_off^-1))&(1<<1);
double qri, *cut_bucksqi, *buck1i, *buck2i, *rhoinvi;
vector xi, d;
ineighn = (ineigh = listmiddle->ilist)+listmiddle->inum;
for (; ineigh<ineighn; ++ineigh) { // loop over my atoms
i = *ineigh; fi = f0+3*i;
qri = qqrd2e*q[i];
memcpy(xi, x0+(i+(i<<1)), sizeof(vector));
cut_bucksqi = cut_bucksq[typei = type[i]];
buck1i = buck1[typei]; buck2i = buck2[typei]; rhoinvi = rhoinv[typei];
jneighn = (jneigh = listmiddle->firstneigh[i])+listmiddle->numneigh[i];
for (; jneigh<jneighn; ++jneigh) { // loop over neighbors
j = *jneigh;
ni = sbmask(j);
j &= NEIGHMASK;
{ register double *xj = x0+(j+(j<<1));
d[0] = xi[0] - xj[0]; // pair vector
d[1] = xi[1] - xj[1];
d[2] = xi[2] - xj[2]; }
if ((rsq = vec_dot(d, d)) >= cut_out_off_sq) continue;
if (rsq <= cut_in_off_sq) continue;
r2inv = 1.0/rsq;
r = sqrt(rsq);
if (order1 && (rsq < cut_coulsq)) // coulombic
force_coul = ni == 0 ?
qri*q[j]/r : qri*q[j]/r*special_coul[ni];
if (rsq < cut_bucksqi[typej = type[j]]) { // buckingham
register double rn = r2inv*r2inv*r2inv,
expr = exp(-r*rhoinvi[typej]);
force_buck = ni == 0 ?
(r*expr*buck1i[typej]-rn*buck2i[typej]) :
(r*expr*buck1i[typej]-rn*buck2i[typej])*special_lj[ni];
}
else force_buck = 0.0;
fpair = (force_coul + force_buck) * r2inv;
if (rsq < cut_in_on_sq) { // switching
register double rsw = (sqrt(rsq) - cut_in_off)/cut_in_diff;
fpair *= rsw*rsw*(3.0 - 2.0*rsw);
}
if (rsq > cut_out_on_sq) {
register double rsw = (sqrt(rsq) - cut_out_on)/cut_out_diff;
fpair *= 1.0 + rsw*rsw*(2.0*rsw-3.0);
}
if (newton_pair || j < nlocal) { // force update
register double *fj = f0+(j+(j<<1)), f;
fi[0] += f = d[0]*fpair; fj[0] -= f;
fi[1] += f = d[1]*fpair; fj[1] -= f;
fi[2] += f = d[2]*fpair; fj[2] -= f;
}
else {
fi[0] += d[0]*fpair;
fi[1] += d[1]*fpair;
fi[2] += d[2]*fpair;
}
}
}
}
/* ---------------------------------------------------------------------- */
void PairBuckDispCoulLong::compute_outer(int eflag, int vflag)
{
double evdwl,ecoul,fpair;
evdwl = ecoul = 0.0;
if (eflag || vflag) ev_setup(eflag,vflag);
else evflag = 0;
double **x = atom->x, *x0 = x[0];
double **f = atom->f, *f0 = f[0], *fi = f0;
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;
int i, j, order1 = ewald_order&(1<<1), order6 = ewald_order&(1<<6);
int *ineigh, *ineighn, *jneigh, *jneighn, typei, typej, ni, respa_flag;
double qi = 0.0, qri = 0.0, *cutsqi, *cut_bucksqi,
*buck1i, *buck2i, *buckai, *buckci, *rhoinvi, *offseti;
double r, rsq, r2inv, force_coul, force_buck;
double g2 = g_ewald_6*g_ewald_6, g6 = g2*g2*g2, g8 = g6*g2;
double respa_buck = 0.0, respa_coul = 0.0, frespa = 0.0;
vector xi, d;
double cut_in_off = cut_respa[2];
double cut_in_on = cut_respa[3];
double cut_in_diff = cut_in_on - cut_in_off;
double cut_in_off_sq = cut_in_off*cut_in_off;
double cut_in_on_sq = cut_in_on*cut_in_on;
ineighn = (ineigh = listouter->ilist)+listouter->inum;
for (; ineigh<ineighn; ++ineigh) { // loop over my atoms
i = *ineigh; fi = f0+3*i;
if (order1) qri = (qi = q[i])*qqrd2e; // initialize constants
offseti = offset[typei = type[i]];
buck1i = buck1[typei]; buck2i = buck2[typei];
buckai = buck_a[typei]; buckci = buck_c[typei]; rhoinvi = rhoinv[typei];
cutsqi = cutsq[typei]; cut_bucksqi = cut_bucksq[typei];
memcpy(xi, x0+(i+(i<<1)), sizeof(vector));
jneighn = (jneigh = listouter->firstneigh[i])+listouter->numneigh[i];
for (; jneigh<jneighn; ++jneigh) { // loop over neighbors
j = *jneigh;
ni = sbmask(j);
j &= NEIGHMASK;
{ register double *xj = x0+(j+(j<<1));
d[0] = xi[0] - xj[0]; // pair vector
d[1] = xi[1] - xj[1];
d[2] = xi[2] - xj[2]; }
if ((rsq = vec_dot(d, d)) >= cutsqi[typej = type[j]]) continue;
r2inv = 1.0/rsq;
r = sqrt(rsq);
if ((respa_flag = (rsq>cut_in_off_sq)&&(rsq<cut_in_on_sq))) {
register double rsw = (r-cut_in_off)/cut_in_diff;
frespa = rsw*rsw*(3.0-2.0*rsw);
}
if (order1 && (rsq < cut_coulsq)) { // coulombic
if (!ncoultablebits || rsq <= tabinnersq) { // series real space
register double s = qri*q[j];
if (respa_flag) // correct for respa
respa_coul = ni == 0 ? frespa*s/r : frespa*s/r*special_coul[ni];
register double x = g_ewald*r, t = 1.0/(1.0+EWALD_P*x);
if (ni == 0) {
s *= g_ewald*exp(-x*x);
force_coul = (t *= ((((t*A5+A4)*t+A3)*t+A2)*t+A1)*s/x)+EWALD_F*s;
if (eflag) ecoul = t;
}
else { // correct for special
r = s*(1.0-special_coul[ni])/r; s *= g_ewald*exp(-x*x);
force_coul = (t *= ((((t*A5+A4)*t+A3)*t+A2)*t+A1)*s/x)+EWALD_F*s-r;
if (eflag) ecoul = t-r;
}
} // table real space
else {
if (respa_flag) respa_coul = ni == 0 ? // correct for respa
frespa*qri*q[j]/r :
frespa*qri*q[j]/r*special_coul[ni];
register union_int_float_t t;
t.f = rsq;
register const int k = (t.i & ncoulmask) >> ncoulshiftbits;
register double f = (rsq-rtable[k])*drtable[k], qiqj = qi*q[j];
if (ni == 0) {
force_coul = qiqj*(ftable[k]+f*dftable[k]);
if (eflag) ecoul = qiqj*(etable[k]+f*detable[k]);
}
else { // correct for special
t.f = (1.0-special_coul[ni])*(ctable[k]+f*dctable[k]);
force_coul = qiqj*(ftable[k]+f*dftable[k]-t.f);
if (eflag) ecoul = qiqj*(etable[k]+f*detable[k]-t.f);
}
}
}
else force_coul = respa_coul = ecoul = 0.0;
if (rsq < cut_bucksqi[typej]) { // buckingham
register double rn = r2inv*r2inv*r2inv,
expr = exp(-r*rhoinvi[typej]);
if (respa_flag) respa_buck = ni == 0 ? // correct for respa
frespa*(r*expr*buck1i[typej]-rn*buck2i[typej]) :
frespa*(r*expr*buck1i[typej]-rn*buck2i[typej])*special_lj[ni];
if (order6) { // long-range form
register double x2 = g2*rsq, a2 = 1.0/x2;
x2 = a2*exp(-x2)*buckci[typej];
if (ni == 0) {
force_buck =
r*expr*buck1i[typej]-g8*(((6.0*a2+6.0)*a2+3.0)*a2+1.0)*x2*rsq;
if (eflag) evdwl = expr*buckai[typej]-g6*((a2+1.0)*a2+0.5)*x2;
}
else { // correct for special
register double f = special_lj[ni], t = rn*(1.0-f);
force_buck = f*r*expr*buck1i[typej]-
g8*(((6.0*a2+6.0)*a2+3.0)*a2+1.0)*x2*rsq+t*buck2i[typej];
if (eflag) evdwl = f*expr*buckai[typej] -
g6*((a2+1.0)*a2+0.5)*x2+t*buckci[typej];
}
}
else { // cut form
if (ni == 0) {
force_buck = r*expr*buck1i[typej]-rn*buck2i[typej];
if (eflag)
evdwl = expr*buckai[typej]-rn*buckci[typej]-offseti[typej];
}
else { // correct for special
register double f = special_lj[ni];
force_buck = f*(r*expr*buck1i[typej]-rn*buck2i[typej]);
if (eflag)
evdwl = f*(expr*buckai[typej]-rn*buckci[typej]-offseti[typej]);
}
}
}
else force_buck = respa_buck = evdwl = 0.0;
fpair = (force_coul+force_buck)*r2inv;
frespa = fpair-(respa_coul+respa_buck)*r2inv;
if (newton_pair || j < nlocal) {
register double *fj = f0+(j+(j<<1)), f;
fi[0] += f = d[0]*frespa; fj[0] -= f;
fi[1] += f = d[1]*frespa; fj[1] -= f;
fi[2] += f = d[2]*frespa; fj[2] -= f;
}
else {
fi[0] += d[0]*frespa;
fi[1] += d[1]*frespa;
fi[2] += d[2]*frespa;
}
if (evflag) ev_tally(i,j,nlocal,newton_pair,
evdwl,ecoul,fpair,d[0],d[1],d[2]);
}
}
}
/* ----------------------------------------------------------------------
setup force tables used in compute routines
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::init_tables()
{
int masklo,maskhi;
double r,grij,expm2,derfc,rsw;
double qqrd2e = force->qqrd2e;
tabinnersq = tabinner*tabinner;
init_bitmap(tabinner,cut_coul,ncoultablebits,
masklo,maskhi,ncoulmask,ncoulshiftbits);
int ntable = 1;
for (int i = 0; i < ncoultablebits; i++) ntable *= 2;
// linear lookup tables of length N = 2^ncoultablebits
// stored value = value at lower edge of bin
// d values = delta from lower edge to upper edge of bin
if (ftable) free_tables();
memory->create(rtable,ntable,"pair:rtable");
memory->create(ftable,ntable,"pair:ftable");
memory->create(ctable,ntable,"pair:ctable");
memory->create(etable,ntable,"pair:etable");
memory->create(drtable,ntable,"pair:drtable");
memory->create(dftable,ntable,"pair:dftable");
memory->create(dctable,ntable,"pair:dctable");
memory->create(detable,ntable,"pair:detable");
if (cut_respa == NULL) {
vtable = ptable = dvtable = dptable = NULL;
} else {
memory->create(vtable,ntable,"pair:vtable");
memory->create(ptable,ntable,"pair:ptable");
memory->create(dvtable,ntable,"pair:dvtable");
memory->create(dptable,ntable,"pair:dptable");
}
union_int_float_t rsq_lookup;
union_int_float_t minrsq_lookup;
int itablemin;
minrsq_lookup.i = 0 << ncoulshiftbits;
minrsq_lookup.i |= maskhi;
for (int i = 0; i < ntable; i++) {
rsq_lookup.i = i << ncoulshiftbits;
rsq_lookup.i |= masklo;
if (rsq_lookup.f < tabinnersq) {
rsq_lookup.i = i << ncoulshiftbits;
rsq_lookup.i |= maskhi;
}
r = sqrt(rsq_lookup.f);
grij = g_ewald * r;
expm2 = exp(-grij*grij);
derfc = erfc(grij);
if (cut_respa == NULL) {
rtable[i] = rsq_lookup.f;
ftable[i] = qqrd2e/r * (derfc + EWALD_F*grij*expm2);
ctable[i] = qqrd2e/r;
etable[i] = qqrd2e/r * derfc;
} else {
rtable[i] = rsq_lookup.f;
ftable[i] = qqrd2e/r * (derfc + EWALD_F*grij*expm2 - 1.0);
ctable[i] = 0.0;
etable[i] = qqrd2e/r * derfc;
ptable[i] = qqrd2e/r;
vtable[i] = qqrd2e/r * (derfc + EWALD_F*grij*expm2);
if (rsq_lookup.f > cut_respa[2]*cut_respa[2]) {
if (rsq_lookup.f < cut_respa[3]*cut_respa[3]) {
rsw = (r - cut_respa[2])/(cut_respa[3] - cut_respa[2]);
ftable[i] += qqrd2e/r * rsw*rsw*(3.0 - 2.0*rsw);
ctable[i] = qqrd2e/r * rsw*rsw*(3.0 - 2.0*rsw);
} else {
ftable[i] = qqrd2e/r * (derfc + EWALD_F*grij*expm2);
ctable[i] = qqrd2e/r;
}
}
}
minrsq_lookup.f = MIN(minrsq_lookup.f,rsq_lookup.f);
}
tabinnersq = minrsq_lookup.f;
int ntablem1 = ntable - 1;
for (int i = 0; i < ntablem1; i++) {
drtable[i] = 1.0/(rtable[i+1] - rtable[i]);
dftable[i] = ftable[i+1] - ftable[i];
dctable[i] = ctable[i+1] - ctable[i];
detable[i] = etable[i+1] - etable[i];
}
if (cut_respa) {
for (int i = 0; i < ntablem1; i++) {
dvtable[i] = vtable[i+1] - vtable[i];
dptable[i] = ptable[i+1] - ptable[i];
}
}
// get the delta values for the last table entries
// tables are connected periodically between 0 and ntablem1
drtable[ntablem1] = 1.0/(rtable[0] - rtable[ntablem1]);
dftable[ntablem1] = ftable[0] - ftable[ntablem1];
dctable[ntablem1] = ctable[0] - ctable[ntablem1];
detable[ntablem1] = etable[0] - etable[ntablem1];
if (cut_respa) {
dvtable[ntablem1] = vtable[0] - vtable[ntablem1];
dptable[ntablem1] = ptable[0] - ptable[ntablem1];
}
// get the correct delta values at itablemax
// smallest r is in bin itablemin
// largest r is in bin itablemax, which is itablemin-1,
// or ntablem1 if itablemin=0
// deltas at itablemax only needed if corresponding rsq < cut*cut
// if so, compute deltas between rsq and cut*cut
double f_tmp,c_tmp,e_tmp,p_tmp = 0.0,v_tmp = 0.0;
itablemin = minrsq_lookup.i & ncoulmask;
itablemin >>= ncoulshiftbits;
int itablemax = itablemin - 1;
if (itablemin == 0) itablemax = ntablem1;
rsq_lookup.i = itablemax << ncoulshiftbits;
rsq_lookup.i |= maskhi;
if (rsq_lookup.f < cut_coulsq) {
rsq_lookup.f = cut_coulsq;
r = sqrtf(rsq_lookup.f);
grij = g_ewald * r;
expm2 = exp(-grij*grij);
derfc = erfc(grij);
if (cut_respa == NULL) {
f_tmp = qqrd2e/r * (derfc + EWALD_F*grij*expm2);
c_tmp = qqrd2e/r;
e_tmp = qqrd2e/r * derfc;
} else {
f_tmp = qqrd2e/r * (derfc + EWALD_F*grij*expm2 - 1.0);
c_tmp = 0.0;
e_tmp = qqrd2e/r * derfc;
p_tmp = qqrd2e/r;
v_tmp = qqrd2e/r * (derfc + EWALD_F*grij*expm2);
if (rsq_lookup.f > cut_respa[2]*cut_respa[2]) {
if (rsq_lookup.f < cut_respa[3]*cut_respa[3]) {
rsw = (r - cut_respa[2])/(cut_respa[3] - cut_respa[2]);
f_tmp += qqrd2e/r * rsw*rsw*(3.0 - 2.0*rsw);
c_tmp = qqrd2e/r * rsw*rsw*(3.0 - 2.0*rsw);
} else {
f_tmp = qqrd2e/r * (derfc + EWALD_F*grij*expm2);
c_tmp = qqrd2e/r;
}
}
}
drtable[itablemax] = 1.0/(rsq_lookup.f - rtable[itablemax]);
dftable[itablemax] = f_tmp - ftable[itablemax];
dctable[itablemax] = c_tmp - ctable[itablemax];
detable[itablemax] = e_tmp - etable[itablemax];
if (cut_respa) {
dvtable[itablemax] = v_tmp - vtable[itablemax];
dptable[itablemax] = p_tmp - ptable[itablemax];
}
}
}
/* ----------------------------------------------------------------------
free memory for tables used in pair computations
------------------------------------------------------------------------- */
void PairBuckDispCoulLong::free_tables()
{
memory->destroy(rtable);
memory->destroy(drtable);
memory->destroy(ftable);
memory->destroy(dftable);
memory->destroy(ctable);
memory->destroy(dctable);
memory->destroy(etable);
memory->destroy(detable);
memory->destroy(vtable);
memory->destroy(dvtable);
memory->destroy(ptable);
memory->destroy(dptable);
}
/* ---------------------------------------------------------------------- */
double PairBuckDispCoulLong::single(int i, int j, int itype, int jtype,
double rsq, double factor_coul, double factor_buck,
double &fforce)
{
double f, r, r2inv, r6inv, force_coul, force_buck;
double g2 = g_ewald_6*g_ewald_6, g6 = g2*g2*g2, g8 = g6*g2, *q = atom->q;
r = sqrt(rsq);
r2inv = 1.0/rsq;
double eng = 0.0;
if ((ewald_order&2) && (rsq < cut_coulsq)) { // coulombic
if (!ncoultablebits || rsq <= tabinnersq) { // series real space
register double x = g_ewald*r;
register double s = force->qqrd2e*q[i]*q[j], t = 1.0/(1.0+EWALD_P*x);
f = s*(1.0-factor_coul)/r; s *= g_ewald*exp(-x*x);
force_coul = (t *= ((((t*A5+A4)*t+A3)*t+A2)*t+A1)*s/x)+EWALD_F*s-f;
eng += t-f;
}
else { // table real space
register union_int_float_t t;
t.f = rsq;
register const int k = (t.i & ncoulmask) >> ncoulshiftbits;
register double f = (rsq-rtable[k])*drtable[k], qiqj = q[i]*q[j];
t.f = (1.0-factor_coul)*(ctable[k]+f*dctable[k]);
force_coul = qiqj*(ftable[k]+f*dftable[k]-t.f);
eng += qiqj*(etable[k]+f*detable[k]-t.f);
}
} else force_coul = 0.0;
if (rsq < cut_bucksq[itype][jtype]) { // buckingham
register double expr = factor_buck*exp(-sqrt(rsq)*rhoinv[itype][jtype]);
r6inv = r2inv*r2inv*r2inv;
if (ewald_order&64) { // long-range
register double x2 = g2*rsq, a2 = 1.0/x2, t = r6inv*(1.0-factor_buck);
x2 = a2*exp(-x2)*buck_c[itype][jtype];
force_buck = buck1[itype][jtype]*r*expr-
g8*(((6.0*a2+6.0)*a2+3.0)*a2+a2)*x2*rsq+t*buck2[itype][jtype];
eng += buck_a[itype][jtype]*expr-
g6*((a2+1.0)*a2+0.5)*x2+t*buck_c[itype][jtype];
}
else { // cut
force_buck =
buck1[itype][jtype]*r*expr-factor_buck*buck_c[itype][jtype]*r6inv;
eng += buck_a[itype][jtype]*expr-
factor_buck*(buck_c[itype][jtype]*r6inv-offset[itype][jtype]);
}
} else force_buck = 0.0;
fforce = (force_coul+force_buck)*r2inv;
return eng;
}

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