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lammps/src/DIPOLE/pair_lj_long_dipole_long.cpp
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pair_lj_long_dipole_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 and Stan Moore (Sandia)
------------------------------------------------------------------------- */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "math_const.h"
#include "math_vector.h"
#include "pair_lj_long_dipole_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;
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
// ----------------------------------------------------------------------
PairLJLongDipoleLong::PairLJLongDipoleLong(LAMMPS *lmp) : Pair(lmp)
{
dispersionflag = ewaldflag = dipoleflag = 1;
respa_enable = 0;
single_enable = 0;
}
// ----------------------------------------------------------------------
// global settings
// ----------------------------------------------------------------------
void PairLJLongDipoleLong::options(char **arg, int order)
{
const char *option[] = {"long", "cut", "off", NULL};
int i;
if (!*arg) error->all(FLERR,"Illegal pair_style lj/long/dipole/long command");
for (i=0; option[i]&&strcmp(arg[0], option[i]); ++i);
switch (i) {
default: error->all(FLERR,"Illegal pair_style lj/long/dipole/long command");
case 0: ewald_order |= 1<<order; break; // set kspace r^-order
case 2: ewald_off |= 1<<order; // turn r^-order off
case 1: break;
}
}
void PairLJLongDipoleLong::settings(int narg, char **arg)
{
if (narg != 3 && narg != 4) error->all(FLERR,"Illegal pair_style command");
ewald_off = 0;
ewald_order = 0;
options(arg, 6);
options(++arg, 3);
options(arg, 1);
if (!comm->me && ewald_order&(1<<6))
error->warning(FLERR,"Geometric mixing assumed for 1/r^6 coefficients");
if (!comm->me && ewald_order==((1<<3)|(1<<6)))
error->warning(FLERR,
"Using largest cut-off for lj/long/dipole/long long long");
if (!*(++arg))
error->all(FLERR,"Cut-offs missing in pair_style lj/long/dipole/long");
if (!((ewald_order^ewald_off)&(1<<3)))
error->all(FLERR,
"Coulombic cut not supported in pair_style lj/long/dipole/long");
cut_lj_global = force->numeric(FLERR,*(arg++));
if (narg == 4 && (ewald_order==74))
error->all(FLERR,"Only one cut-off allowed when requesting all long");
if (narg == 4) cut_coul = force->numeric(FLERR,*(arg++));
else cut_coul = cut_lj_global;
if (allocated) { // reset explicit cuts
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;
}
}
// ----------------------------------------------------------------------
// free all arrays
// ----------------------------------------------------------------------
PairLJLongDipoleLong::~PairLJLongDipoleLong()
{
if (allocated) {
memory->destroy(setflag);
memory->destroy(cutsq);
memory->destroy(cut_lj_read);
memory->destroy(cut_lj);
memory->destroy(cut_ljsq);
memory->destroy(epsilon_read);
memory->destroy(epsilon);
memory->destroy(sigma_read);
memory->destroy(sigma);
memory->destroy(lj1);
memory->destroy(lj2);
memory->destroy(lj3);
memory->destroy(lj4);
memory->destroy(offset);
}
//if (ftable) free_tables();
}
/* ----------------------------------------------------------------------
allocate all arrays
------------------------------------------------------------------------- */
void PairLJLongDipoleLong::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_read,n+1,n+1,"pair:cut_lj_read");
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_read,n+1,n+1,"pair:epsilon_read");
memory->create(epsilon,n+1,n+1,"pair:epsilon");
memory->create(sigma_read,n+1,n+1,"pair:sigma_read");
memory->create(sigma,n+1,n+1,"pair:sigma");
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");
}
/* ----------------------------------------------------------------------
extract protected data from object
------------------------------------------------------------------------- */
void *PairLJLongDipoleLong::extract(const char *id, int &dim)
{
const char *ids[] = {
"B", "sigma", "epsilon", "ewald_order", "ewald_cut", "ewald_mix",
"cut_coul", "cut_vdwl", NULL};
void *ptrs[] = {
lj4, sigma, epsilon, &ewald_order, &cut_coul, &mix_flag, &cut_coul,
&cut_lj_global, NULL};
int i;
for (i=0; ids[i]&&strcmp(ids[i], id); ++i);
if (i <= 2) dim = 2;
else dim = 0;
return ptrs[i];
}
/* ----------------------------------------------------------------------
set coeffs for one or more type pairs
------------------------------------------------------------------------- */
void PairLJLongDipoleLong::coeff(int narg, char **arg)
{
if (narg < 4 || narg > 5)
error->all(FLERR,"Incorrect args for pair coefficients");
if (!allocated) allocate();
int ilo,ihi,jlo,jhi;
force->bounds(FLERR,arg[0],atom->ntypes,ilo,ihi);
force->bounds(FLERR,arg[1],atom->ntypes,jlo,jhi);
double epsilon_one = force->numeric(FLERR,arg[2]);
double sigma_one = force->numeric(FLERR,arg[3]);
double cut_lj_one = cut_lj_global;
if (narg == 5) cut_lj_one = force->numeric(FLERR,arg[4]);
int count = 0;
for (int i = ilo; i <= ihi; i++) {
for (int j = MAX(jlo,i); j <= jhi; j++) {
epsilon_read[i][j] = epsilon_one;
sigma_read[i][j] = sigma_one;
cut_lj_read[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 PairLJLongDipoleLong::init_style()
{
const char *style3[] = {"ewald/disp", NULL};
const char *style6[] = {"ewald/disp", NULL};
int i;
if (strcmp(update->unit_style,"electron") == 0)
error->all(FLERR,"Cannot (yet) use 'electron' units with dipoles");
// require an atom style with charge defined
if (!atom->q_flag && (ewald_order&(1<<1)))
error->all(FLERR,
"Invoking coulombic in pair style lj/long/dipole/long requires atom attribute q");
if (!atom->mu && (ewald_order&(1<<3)))
error->all(FLERR,"Pair lj/long/dipole/long requires atom attributes mu, torque");
if (!atom->torque && (ewald_order&(1<<3)))
error->all(FLERR,"Pair lj/long/dipole/long requires atom attributes mu, torque");
neighbor->request(this,instance_me);
cut_coulsq = cut_coul * cut_coul;
// ensure use of KSpace long-range solver, set g_ewald
if (ewald_order&(1<<3)) { // r^-1 kspace
if (force->kspace == NULL)
error->all(FLERR,"Pair style requires a KSpace style");
for (i=0; style3[i]&&strcmp(force->kspace_style, style3[i]); ++i);
if (!style3[i])
error->all(FLERR,"Pair style requires use of kspace_style ewald/disp");
}
if (ewald_order&(1<<6)) { // r^-6 kspace
if (force->kspace == NULL)
error->all(FLERR,"Pair style requires a KSpace style");
for (i=0; style6[i]&&strcmp(force->kspace_style, style6[i]); ++i);
if (!style6[i])
error->all(FLERR,"Pair style requires use of kspace_style ewald/disp");
}
if (force->kspace) g_ewald = force->kspace->g_ewald;
}
/* ----------------------------------------------------------------------
init for one type pair i,j and corresponding j,i
------------------------------------------------------------------------- */
double PairLJLongDipoleLong::init_one(int i, int j)
{
if ((ewald_order&(1<<6))||(setflag[i][j] == 0)) {
epsilon[i][j] = mix_energy(epsilon_read[i][i],epsilon_read[j][j],
sigma_read[i][i],sigma_read[j][j]);
sigma[i][j] = mix_distance(sigma_read[i][i],sigma_read[j][j]);
if (ewald_order&(1<<6))
cut_lj[i][j] = cut_lj_global;
else
cut_lj[i][j] = mix_distance(cut_lj_read[i][i],cut_lj_read[j][j]);
}
else {
sigma[i][j] = sigma_read[i][j];
epsilon[i][j] = epsilon_read[i][j];
cut_lj[i][j] = cut_lj_read[i][j];
}
double cut = MAX(cut_lj[i][j], cut_coul);
cutsq[i][j] = cut*cut;
cut_ljsq[i][j] = cut_lj[i][j] * cut_lj[i][j];
lj1[i][j] = 48.0 * epsilon[i][j] * pow(sigma[i][j],12.0);
lj2[i][j] = 24.0 * epsilon[i][j] * pow(sigma[i][j],6.0);
lj3[i][j] = 4.0 * epsilon[i][j] * pow(sigma[i][j],12.0);
lj4[i][j] = 4.0 * epsilon[i][j] * pow(sigma[i][j],6.0);
// check interior rRESPA cutoff
//if (cut_respa && MIN(cut_lj[i][j],cut_coul) < cut_respa[3])
//error->all(FLERR,"Pair cutoff < Respa interior cutoff");
if (offset_flag && (cut_lj[i][j] > 0.0)) {
double ratio = sigma[i][j] / cut_lj[i][j];
offset[i][j] = 4.0 * epsilon[i][j] * (pow(ratio,12.0) - pow(ratio,6.0));
} else offset[i][j] = 0.0;
cutsq[j][i] = cutsq[i][j];
cut_ljsq[j][i] = cut_ljsq[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];
return cut;
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairLJLongDipoleLong::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_read[i][j],sizeof(double),1,fp);
fwrite(&sigma_read[i][j],sizeof(double),1,fp);
fwrite(&cut_lj_read[i][j],sizeof(double),1,fp);
}
}
}
/* ----------------------------------------------------------------------
proc 0 reads from restart file, bcasts
------------------------------------------------------------------------- */
void PairLJLongDipoleLong::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(&epsilon_read[i][j],sizeof(double),1,fp);
fread(&sigma_read[i][j],sizeof(double),1,fp);
fread(&cut_lj_read[i][j],sizeof(double),1,fp);
}
MPI_Bcast(&epsilon_read[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&sigma_read[i][j],1,MPI_DOUBLE,0,world);
MPI_Bcast(&cut_lj_read[i][j],1,MPI_DOUBLE,0,world);
}
}
}
/* ----------------------------------------------------------------------
proc 0 writes to restart file
------------------------------------------------------------------------- */
void PairLJLongDipoleLong::write_restart_settings(FILE *fp)
{
fwrite(&cut_lj_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 PairLJLongDipoleLong::read_restart_settings(FILE *fp)
{
if (comm->me == 0) {
fread(&cut_lj_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_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(&ewald_order,1,MPI_INT,0,world);
}
/* ----------------------------------------------------------------------
compute pair interactions
------------------------------------------------------------------------- */
void PairLJLongDipoleLong::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 **mu = atom->mu, *mu0 = mu[0], *imu, *jmu;
double **tq = atom->torque, *tq0 = tq[0], *tqi;
double **f = atom->f, *f0 = f[0], *fi = f0, fx, fy, fz;
double *q = atom->q, qi = 0, qj;
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;
int order3 = ewald_order&(1<<3), order6 = ewald_order&(1<<6);
int *ineigh, *ineighn, *jneigh, *jneighn, typei, typej, ni;
double *cutsqi, *cut_ljsqi, *lj1i, *lj2i, *lj3i, *lj4i, *offseti;
double rsq, r2inv, force_coul, force_lj;
double g2 = g_ewald*g_ewald, g6 = g2*g2*g2, g8 = g6*g2;
double B0, B1, B2, B3, G0, G1, G2, mudi, mudj, muij;
vector force_d = VECTOR_NULL, ti = VECTOR_NULL, tj = VECTOR_NULL;
vector mui, muj, xi, d;
double C1 = 2.0 * g_ewald / MY_PIS;
double C2 = 2.0 * g2 * C1;
double C3 = 2.0 * g2 * C2;
ineighn = (ineigh = list->ilist)+list->inum;
for (; ineigh<ineighn; ++ineigh) { // loop over all neighs
i = *ineigh; fi = f0+3*i; tqi = tq0+3*i;
qi = q[i]; // initialize constants
offseti = offset[typei = type[i]];
lj1i = lj1[typei]; lj2i = lj2[typei]; lj3i = lj3[typei]; lj4i = lj4[typei];
cutsqi = cutsq[typei]; cut_ljsqi = cut_ljsq[typei];
memcpy(xi, x0+(i+(i<<1)), sizeof(vector));
memcpy(mui, imu = mu0+(i<<2), sizeof(vector));
jneighn = (jneigh = list->firstneigh[i])+list->numneigh[i];
for (; jneigh<jneighn; ++jneigh) { // loop over neighbors
j = *jneigh;
ni = sbmask(j); // special index
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;
if (order3 && (rsq < cut_coulsq)) { // dipole
memcpy(muj, jmu = mu0+(j<<2), sizeof(vector));
{ // series real space
register double r = sqrt(rsq);
register double x = g_ewald*r;
register double f = exp(-x*x)*qqrd2e;
B0 = 1.0/(1.0+EWALD_P*x); // eqn 2.8
B0 *= ((((A5*B0+A4)*B0+A3)*B0+A2)*B0+A1)*f/r;
B1 = (B0 + C1 * f) * r2inv;
B2 = (3.0*B1 + C2 * f) * r2inv;
B3 = (5.0*B2 + C3 * f) * r2inv;
mudi = mui[0]*d[0]+mui[1]*d[1]+mui[2]*d[2];
mudj = muj[0]*d[0]+muj[1]*d[1]+muj[2]*d[2];
muij = mui[0]*muj[0]+mui[1]*muj[1]+mui[2]*muj[2];
G0 = qi*(qj = q[j]); // eqn 2.10
G1 = qi*mudj-qj*mudi+muij;
G2 = -mudi*mudj;
force_coul = G0*B1+G1*B2+G2*B3;
mudi *= B2; mudj *= B2; // torque contribs
ti[0] = mudj*d[0]+(qj*d[0]-muj[0])*B1;
ti[1] = mudj*d[1]+(qj*d[1]-muj[1])*B1;
ti[2] = mudj*d[2]+(qj*d[2]-muj[2])*B1;
if (newton_pair || j < nlocal) {
tj[0] = mudi*d[0]-(qi*d[0]+mui[0])*B1;
tj[1] = mudi*d[1]-(qi*d[1]+mui[1])*B1;
tj[2] = mudi*d[2]-(qi*d[2]+mui[2])*B1;
}
if (eflag) ecoul = G0*B0+G1*B1+G2*B2;
if (ni > 0) { // adj part, eqn 2.13
force_coul -= (f = qqrd2e*(1.0-special_coul[ni])/r)*(
(3.0*G1+15.0*G2*r2inv)*r2inv+G0)*r2inv;
if (eflag)
ecoul -= f*((G1+3.0*G2*r2inv)*r2inv+G0);
B1 -= f*r2inv;
}
B0 = mudj+qj*B1; B3 = -qi*B1+mudi; // position independent
if (ni > 0) B0 -= f*3.0*mudj*r2inv*r2inv/B2;
if (ni > 0) B3 -= f*3.0*mudi*r2inv*r2inv/B2;
force_d[0] = B0*mui[0]+B3*muj[0]; // force contribs
force_d[1] = B0*mui[1]+B3*muj[1];
force_d[2] = B0*mui[2]+B3*muj[2];
if (ni > 0) {
ti[0] -= f*(3.0*mudj*r2inv*r2inv*d[0]/B2+(qj*r2inv*d[0]-muj[0]*r2inv));
ti[1] -= f*(3.0*mudj*r2inv*r2inv*d[1]/B2+(qj*r2inv*d[1]-muj[1]*r2inv));
ti[2] -= f*(3.0*mudj*r2inv*r2inv*d[2]/B2+(qj*r2inv*d[2]-muj[2]*r2inv));
if (newton_pair || j < nlocal) {
tj[0] -= f*(3.0*mudi*r2inv*r2inv*d[0]/B2-(qi*r2inv*d[0]+mui[0]*r2inv));
tj[1] -= f*(3.0*mudi*r2inv*r2inv*d[1]/B2-(qi*r2inv*d[1]+mui[1]*r2inv));
tj[2] -= f*(3.0*mudi*r2inv*r2inv*d[2]/B2-(qi*r2inv*d[2]+mui[2]*r2inv));
}
}
} // table real space
} else {
force_coul = ecoul = 0.0;
memset(force_d, 0, 3*sizeof(double));
}
if (rsq < cut_ljsqi[typej]) { // lj
if (order6) { // long-range lj
register double rn = r2inv*r2inv*r2inv;
register double x2 = g2*rsq, a2 = 1.0/x2;
x2 = a2*exp(-x2)*lj4i[typej];
if (ni < 0) {
force_lj =
(rn*=rn)*lj1i[typej]-g8*(((6.0*a2+6.0)*a2+3.0)*a2+1.0)*x2*rsq;
if (eflag) evdwl = rn*lj3i[typej]-g6*((a2+1.0)*a2+0.5)*x2;
}
else { // special case
register double f = special_lj[ni], t = rn*(1.0-f);
force_lj = f*(rn *= rn)*lj1i[typej]-
g8*(((6.0*a2+6.0)*a2+3.0)*a2+1.0)*x2*rsq+t*lj2i[typej];
if (eflag) evdwl =
f*rn*lj3i[typej]-g6*((a2+1.0)*a2+0.5)*x2+t*lj4i[typej];
}
}
else { // cut lj
register double rn = r2inv*r2inv*r2inv;
if (ni < 0) {
force_lj = rn*(rn*lj1i[typej]-lj2i[typej]);
if (eflag) evdwl = rn*(rn*lj3i[typej]-lj4i[typej])-offseti[typej];
}
else { // special case
register double f = special_lj[ni];
force_lj = f*rn*(rn*lj1i[typej]-lj2i[typej]);
if (eflag) evdwl = f*(
rn*(rn*lj3i[typej]-lj4i[typej])-offseti[typej]);
}
}
force_lj *= r2inv;
}
else force_lj = evdwl = 0.0;
fpair = force_coul+force_lj; // force
if (newton_pair || j < nlocal) {
register double *fj = f0+(j+(j<<1));
fi[0] += fx = d[0]*fpair+force_d[0]; fj[0] -= fx;
fi[1] += fy = d[1]*fpair+force_d[1]; fj[1] -= fy;
fi[2] += fz = d[2]*fpair+force_d[2]; fj[2] -= fz;
tqi[0] += mui[1]*ti[2]-mui[2]*ti[1]; // torque
tqi[1] += mui[2]*ti[0]-mui[0]*ti[2];
tqi[2] += mui[0]*ti[1]-mui[1]*ti[0];
register double *tqj = tq0+(j+(j<<1));
tqj[0] += muj[1]*tj[2]-muj[2]*tj[1];
tqj[1] += muj[2]*tj[0]-muj[0]*tj[2];
tqj[2] += muj[0]*tj[1]-muj[1]*tj[0];
}
else {
fi[0] += fx = d[0]*fpair+force_d[0]; // force
fi[1] += fy = d[1]*fpair+force_d[1];
fi[2] += fz = d[2]*fpair+force_d[2];
tqi[0] += mui[1]*ti[2]-mui[2]*ti[1]; // torque
tqi[1] += mui[2]*ti[0]-mui[0]*ti[2];
tqi[2] += mui[0]*ti[1]-mui[1]*ti[0];
}
if (evflag) ev_tally_xyz(i,j,nlocal,newton_pair,
evdwl,ecoul,fx,fy,fz,d[0],d[1],d[2]);
}
}
if (vflag_fdotr) virial_fdotr_compute();
}
/* ---------------------------------------------------------------------- */
/*
double PairLJLongDipoleLong::single(int i, int j, int itype, int jtype,
double rsq, double factor_coul, double factor_lj,
double &fforce)
{
double r6inv, force_coul, force_lj;
double g2 = g_ewald*g_ewald, g6 = g2*g2*g2, g8 = g6*g2, *q = atom->q;
double eng = 0.0;
double r2inv = 1.0/rsq;
if ((ewald_order&(1<<3)) && (rsq < cut_coulsq)) { // coulombic
double *mui = atom->mu[i], *muj = atom->mu[j];
double *xi = atom->x[i], *xj = atom->x[j];
double qi = q[i], qj = q[j];
double G0, G1, G2, B0, B1, B2, B3, mudi, mudj, muij;
vector d = {xi[0]-xj[0], xi[1]-xj[1], xi[2]-xj[2]};
{ // series real space
register double r = sqrt(rsq);
register double x = g_ewald*r;
register double f = exp(-x*x)*qqrd2e;
B0 = 1.0/(1.0+EWALD_P*x); // eqn 2.8
B0 *= ((((A5*B0+A4)*B0+A3)*B0+A2)*B0+A1)*f/r;
B1 = (B0 + C1 * f) * r2inv;
B2 = (3.0*B1 + C2 * f) * r2inv;
B3 = (5.0*B2 + C3 * f) * r2inv;
mudi = mui[0]*d[0]+mui[1]*d[1]+mui[2]*d[2];
mudj = muj[0]*d[0]+muj[1]*d[1]+muj[2]*d[2];
muij = mui[0]*muj[0]+mui[1]*muj[1]+mui[2]*muj[2];
G0 = qi*(qj = q[j]); // eqn 2.10
G1 = qi*mudj-qj*mudi+muij;
G2 = -mudi*mudj;
force_coul = G0*B1+G1*B2+G2*B3;
eng += G0*B0+G1*B1+G2*B2;
if (factor_coul < 1.0) { // adj part, eqn 2.13
force_coul -= (f = force->qqrd2e*(1.0-factor_coul)/r)*(
(3.0*G1+6.0*muij+15.0*G2*r2inv)*r2inv+G0);
eng -= f*((G1+3.0*G2*r2inv)*r2inv+G0);
B1 -= f*r2inv;
}
B0 = mudj*B2-qj*B1; B3 = qi*B1+mudi*B2; // position independent
//force_d[0] = B0*mui[0]+B3*muj[0]; // force contributions
//force_d[1] = B0*mui[1]+B3*muj[1];
//force_d[2] = B0*mui[2]+B3*muj[2];
} // table real space
}
else force_coul = 0.0;
if (rsq < cut_ljsq[itype][jtype]) { // lennard-jones
r6inv = r2inv*r2inv*r2inv;
if (ewald_order&0x40) { // long-range
register double x2 = g2*rsq, a2 = 1.0/x2, t = r6inv*(1.0-factor_lj);
x2 = a2*exp(-x2)*lj4[itype][jtype];
force_lj = factor_lj*(r6inv *= r6inv)*lj1[itype][jtype]-
g8*(((6.0*a2+6.0)*a2+3.0)*a2+a2)*x2*rsq+t*lj2[itype][jtype];
eng += factor_lj*r6inv*lj3[itype][jtype]-
g6*((a2+1.0)*a2+0.5)*x2+t*lj4[itype][jtype];
}
else { // cut
force_lj = factor_lj*r6inv*(lj1[itype][jtype]*r6inv-lj2[itype][jtype]);
eng += factor_lj*(r6inv*(r6inv*lj3[itype][jtype]-
lj4[itype][jtype])-offset[itype][jtype]);
}
}
else force_lj = 0.0;
fforce = (force_coul+force_lj)*r2inv;
return eng;
}
*/
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