Files
lammps/src/AMOEBA/amoeba_induce.cpp
2024-01-25 02:17:28 -05:00

1734 lines
48 KiB
C++

// clang-format off
/* ----------------------------------------------------------------------
LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
https://www.lammps.org/ Sandia National Laboratories
LAMMPS development team: developers@lammps.org
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.
------------------------------------------------------------------------- */
#include "pair_amoeba.h"
#include "amoeba_convolution.h"
#include "atom.h"
#include "comm.h"
#include "domain.h"
#include "error.h"
#include "fix_store_atom.h"
#include "math_const.h"
#include "math_special.h"
#include "my_page.h"
#include "neigh_list.h"
#include "timer.h"
#include <cmath>
using namespace LAMMPS_NS;
using namespace MathConst;
using MathSpecial::cube;
enum{INDUCE,RSD,SETUP_AMOEBA,SETUP_HIPPO,KMPOLE,AMGROUP}; // forward comm
enum{FIELD,ZRSD,TORQUE,UFLD}; // reverse comm
enum{VDWL,REPULSE,QFER,DISP,MPOLE,POLAR,USOLV,DISP_LONG,MPOLE_LONG,POLAR_LONG};
enum{MUTUAL,OPT,TCG,DIRECT};
enum{GEAR,ASPC,LSQR};
enum{BUILD,APPLY};
enum{GORDON1,GORDON2};
static constexpr double DEBYE = 4.80321; // conversion factor from q-Angs (real units) to Debye
/* ----------------------------------------------------------------------
induce = induced dipole moments via pre-conditioned CG solver
adapted from Tinker induce0a() routine
------------------------------------------------------------------------- */
void PairAmoeba::induce()
{
bool done;
int i,j,m,itype,iter;
double polmin;
double eps,epsold;
double epsd,epsp;
double udsum,upsum;
double a,ap,b,bp;
double sum,sump,term;
double reduce[4],allreduce[4];
// set cutoffs, taper coeffs, and PME params
if (use_ewald) choose(POLAR_LONG);
else choose(POLAR);
// owned atoms
int nlocal = atom->nlocal;
// zero out the induced dipoles at each site
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
uind[i][j] = 0.0;
uinp[i][j] = 0.0;
}
}
// get the electrostatic field due to permanent multipoles
dfield0c(field,fieldp);
// reverse comm to sum field,fieldp from ghost atoms to owned atoms
crstyle = FIELD;
comm->reverse_comm(this);
// set induced dipoles to polarizability times direct field
for (i = 0; i < nlocal; i++) {
itype = amtype[i];
for (j = 0; j < 3; j++) {
udir[i][j] = polarity[itype] * field[i][j];
udirp[i][j] = polarity[itype] * fieldp[i][j];
if (pcgguess) {
uind[i][j] = udir[i][j];
uinp[i][j] = udirp[i][j];
}
}
}
// get induced dipoles via the OPT extrapolation method
// NOTE: could rewrite these loops to avoid allocating
// uopt,uoptp with a optorder+1 dimension, just optorder
// since no need to store optorder+1 values after these loops
if (poltyp == OPT) {
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
uopt[i][0][j] = udir[i][j];
uoptp[i][0][j] = udirp[i][j];
}
}
for (m = 1; m <= optorder; m++) {
optlevel = m - 1; // used in umutual1() for fopt,foptp
cfstyle = INDUCE;
comm->forward_comm(this);
ufield0c(field,fieldp);
crstyle = FIELD;
comm->reverse_comm(this);
for (i = 0; i < nlocal; i++) {
itype = amtype[i];
for (j = 0; j < 3; j++) {
uopt[i][m][j] = polarity[itype] * field[i][j];
uoptp[i][m][j] = polarity[itype] * fieldp[i][j];
uind[i][j] = uopt[i][m][j];
uinp[i][j] = uoptp[i][m][j];
}
}
}
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
uind[i][j] = 0.0;
uinp[i][j] = 0.0;
usum[i][j] = 0.0;
usump[i][j] = 0.0;
for (m = 0; m <= optorder; m++) {
usum[i][j] += uopt[i][m][j];
usump[i][j] += uoptp[i][m][j];
uind[i][j] += copt[m]*usum[i][j];
uinp[i][j] += copt[m]*usump[i][j];
}
}
}
}
// set tolerances for computation of mutual induced dipoles
if (poltyp == MUTUAL) {
done = false;
iter = 0;
polmin = 0.00000001;
eps = 100.0;
// estimate induced dipoles using a polynomial predictor
if (use_pred && nualt == maxualt) {
ulspred();
double ***udalt = fixudalt->tstore;
double ***upalt = fixupalt->tstore;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
udsum = 0.0;
upsum = 0.0;
for (m = 0; m < nualt; m++) {
udsum += bpred[m]*udalt[i][m][j];
upsum += bpredp[m]*upalt[i][m][j];
}
uind[i][j] = udsum;
uinp[i][j] = upsum;
}
}
}
// estimate induced dipoles via inertial extended Lagrangian
// not supported for now
// requires uaux,upaux to persist with each atom
// also requires a velocity vector(s) to persist
// also requires updating uaux,upaux in the Verlet integration
/*
if (use_ielscf) {
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
uind[i][j] = uaux[i][j];
uinp[i][j] = upaux[i][j];
}
}
}
*/
// get the electrostatic field due to induced dipoles
cfstyle = INDUCE;
comm->forward_comm(this);
ufield0c(field,fieldp);
crstyle = FIELD;
comm->reverse_comm(this);
// set initial conjugate gradient residual and conjugate vector
for (i = 0; i < nlocal; i++) {
itype = amtype[i];
poli[i] = MAX(polmin,polarity[itype]);
for (j = 0; j < 3; j++) {
if (pcgguess) {
rsd[i][j] = (udir[i][j]-uind[i][j])/poli[i] + field[i][j];
rsdp[i][j] = (udirp[i][j]-uinp[i][j])/poli[i] + fieldp[i][j];
} else {
rsd[i][j] = udir[i][j] / poli[i];
rsdp[i][j] = udirp[i][j] / poli[i];
}
zrsd[i][j] = rsd[i][j];
zrsdp[i][j] = rsdp[i][j];
}
}
if (pcgprec) {
cfstyle = RSD;
comm->forward_comm(this);
uscale0b(BUILD,rsd,rsdp,zrsd,zrsdp);
uscale0b(APPLY,rsd,rsdp,zrsd,zrsdp);
crstyle = ZRSD;
comm->reverse_comm(this);
}
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
conj[i][j] = zrsd[i][j];
conjp[i][j] = zrsdp[i][j];
}
}
// conjugate gradient iteration of the mutual induced dipoles
while (!done) {
iter++;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
vec[i][j] = uind[i][j];
vecp[i][j] = uinp[i][j];
uind[i][j] = conj[i][j];
uinp[i][j] = conjp[i][j];
}
}
cfstyle = INDUCE;
comm->forward_comm(this);
ufield0c(field,fieldp);
crstyle = FIELD;
comm->reverse_comm(this);
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
uind[i][j] = vec[i][j];
uinp[i][j] = vecp[i][j];
vec[i][j] = conj[i][j]/poli[i] - field[i][j];
vecp[i][j] = conjp[i][j]/poli[i] - fieldp[i][j];
}
}
a = 0.0;
ap = 0.0;
sum = 0.0;
sump = 0.0;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
a += conj[i][j]*vec[i][j];
ap += conjp[i][j]*vecp[i][j];
sum += rsd[i][j]*zrsd[i][j];
sump += rsdp[i][j]*zrsdp[i][j];
}
}
reduce[0] = a;
reduce[1] = ap;
reduce[2] = sum;
reduce[3] = sump;
MPI_Allreduce(reduce,allreduce,4,MPI_DOUBLE,MPI_SUM,world);
a = allreduce[0];
ap = allreduce[1];
sum = allreduce[2];
sump = allreduce[3];
if (a != 0.0) a = sum / a;
if (ap != 0.0) ap = sump / ap;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
uind[i][j] = uind[i][j] + a*conj[i][j];
uinp[i][j] = uinp[i][j] + ap*conjp[i][j];
rsd[i][j] = rsd[i][j] - a*vec[i][j];
rsdp[i][j] = rsdp[i][j] - ap*vecp[i][j];
zrsd[i][j] = rsd[i][j];
zrsdp[i][j] = rsdp[i][j];
}
}
if (pcgprec) {
cfstyle = RSD;
comm->forward_comm(this);
uscale0b(APPLY,rsd,rsdp,zrsd,zrsdp);
crstyle = ZRSD;
comm->reverse_comm(this);
}
b = 0.0;
bp = 0.0;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
b += rsd[i][j]*zrsd[i][j];
bp += rsdp[i][j]*zrsdp[i][j];
}
}
reduce[0] = b;
reduce[1] = bp;
MPI_Allreduce(reduce,allreduce,4,MPI_DOUBLE,MPI_SUM,world);
b = allreduce[0];
bp = allreduce[1];
if (sum != 0.0) b /= sum;
if (sump != 0.0) bp /= sump;
epsd = 0.0;
epsp = 0.0;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
conj[i][j] = zrsd[i][j] + b*conj[i][j];
conjp[i][j] = zrsdp[i][j] + bp*conjp[i][j];
epsd += rsd[i][j]*rsd[i][j];
epsp += rsdp[i][j]*rsdp[i][j];
}
}
reduce[0] = epsd;
reduce[1] = epsp;
MPI_Allreduce(reduce,allreduce,4,MPI_DOUBLE,MPI_SUM,world);
epsd = allreduce[0];
epsp = allreduce[1];
// check the convergence of the mutual induced dipoles
epsold = eps;
eps = MAX(epsd,epsp);
eps = DEBYE * sqrt(eps/atom->natoms);
if (eps < poleps) done = true;
// also commented out in induce.f of Tinker
// if (eps > epsold) done = true;
if (iter >= politer) done = true;
// apply a "peek" iteration to the mutual induced dipoles
if (done) {
for (i = 0; i < nlocal; i++) {
term = pcgpeek * poli[i];
for (j = 0; j < 3; j++) {
uind[i][j] += term*rsd[i][j];
uinp[i][j] += term*rsdp[i][j];
}
}
}
}
// terminate the calculation if dipoles failed to converge
// NOTE: could make this an error
if (iter >= politer || eps > epsold)
if (comm->me == 0)
error->warning(FLERR,"AMOEBA induced dipoles did not converge");
}
// update the lists of previous induced dipole values
// shift previous m values up to m+1, add new values at m = 0
// only when preconditioner is used
if (use_pred) {
double ***udalt = fixudalt->tstore;
double ***upalt = fixupalt->tstore;
nualt = MIN(nualt+1,maxualt);
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
for (m = nualt-1; m > 0; m--) {
udalt[i][m][j] = udalt[i][m-1][j];
upalt[i][m][j] = upalt[i][m-1][j];
}
udalt[i][0][j] = uind[i][j];
upalt[i][0][j] = uinp[i][j];
}
}
}
}
/* ----------------------------------------------------------------------
ulspred = induced dipole prediction coeffs
ulspred uses standard extrapolation or a least squares fit
to set coefficients of an induced dipole predictor polynomial
literature references:
J. Kolafa, "Time-Reversible Always Stable Predictor-Corrector
Method for Molecular Dynamics of Polarizable Molecules", Journal
of Computational Chemistry, 25, 335-342 (2004)
W. Wang and R. D. Skeel, "Fast Evaluation of Polarizable Forces",
Journal of Chemical Physics, 123, 164107 (2005)
------------------------------------------------------------------------- */
void PairAmoeba::ulspred()
{
int i,j,k,m;
double coeff,udk,upk;
double amax,apmax;
// set the Gear predictor binomial coefficients
if (polpred == GEAR) {
for (i = 0; i < nualt; i++) {
coeff = gear[i];
bpred[i] = coeff;
bpredp[i] = coeff;
bpreds[i] = coeff;
bpredps[i] = coeff;
}
// set always stable predictor-corrector (ASPC) coefficients
} else if (polpred == ASPC) {
for (i = 0; i < nualt; i++) {
coeff = aspc[i];
bpred[i] = coeff;
bpredp[i] = coeff;
bpreds[i] = coeff;
bpredps[i] = coeff;
}
// derive normal equations corresponding to least squares fit
} else if (polpred == LSQR) {
double ***udalt = fixudalt->tstore;
double ***upalt = fixupalt->tstore;
for (k = 0; k < nualt; k++) {
b_ualt[k] = 0.0;
bp_ualt[k] = 0.0;
for (m = k; m < nualt; m++) {
c_ualt[k][m] = 0.0;
cp_ualt[k][m] = 0.0;
}
}
int nlocal = atom->nlocal;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
for (k = 0; k < nualt; k++) {
udk = udalt[i][k][j];
upk = upalt[i][k][j];
for (m = k; m < nualt; m++) {
c_ualt[k][m] += udk*udalt[i][m][j];
cp_ualt[k][m] += upk*upalt[i][m][j];
}
}
}
}
i = 0;
for (k = 1; k < nualt; k++) {
b_ualt[k-1] = c_ualt[0][k];
bp_ualt[k-1] = cp_ualt[0][k];
for (m = k; m < nualt; m++) {
a_ualt[i] = c_ualt[k][m];
ap_ualt[i] = cp_ualt[k][m];
i++;
}
}
// check for nonzero coefficients and solve normal equations
k = nualt - 1;
amax = 0.0;
apmax = 0.0;
for (i = 0; i < k*(k+1)/2; i++) {
amax = MAX(amax,a_ualt[i]);
apmax = MAX(apmax,ap_ualt[i]);
}
if (amax != 0.0) cholesky(nualt-1,a_ualt,b_ualt);
if (apmax != 0.0) cholesky(nualt-1,ap_ualt,bp_ualt);
// transfer the final solution to the coefficient vector
for (k = 0; k < nualt-1; k++) {
bpred[k] = b_ualt[k];
bpredp[k] = bp_ualt[k];
bpreds[k] = b_ualt[k];
bpredps[k] = bp_ualt[k];
}
bpred[nualt-1] = 0.0;
bpredp[nualt-1] = 0.0;
bpreds[nualt-1] = 0.0;
bpredps[nualt-1] = 0.0;
}
}
/* ----------------------------------------------------------------------
ufield0c = mutual induction via Ewald sum
ufield0c computes the mutual electrostatic field due to
induced dipole moments via Ewald summation
------------------------------------------------------------------------- */
void PairAmoeba::ufield0c(double **field, double **fieldp)
{
int i,j;
double term;
// zero field,fieldp for owned and ghost atoms
int nlocal = atom->nlocal;
int nall = nlocal + atom->nghost;
for (i = 0; i < nall; i++) {
for (j = 0; j < 3; j++) {
field[i][j] = 0.0;
fieldp[i][j] = 0.0;
}
}
double time0, time1, time2;
if (timer->has_sync()) MPI_Barrier(world);
time0 = platform::walltime();
// get the real space portion of the mutual field
if (polar_rspace_flag) umutual2b(field,fieldp);
time1 = platform::walltime();
// get the reciprocal space part of the mutual field
if (polar_kspace_flag) umutual1(field,fieldp);
time2 = platform::walltime();
// add the self-energy portion of the mutual field
term = (4.0/3.0) * aewald*aewald*aewald / MY_PIS;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
field[i][j] += term*uind[i][j];
fieldp[i][j] += term*uinp[i][j];
}
}
// accumulate timing information
time_mutual_rspace += time1 - time0;
time_mutual_kspace += time2 - time1;
}
/* ----------------------------------------------------------------------
uscale0b = dipole preconditioner via neigh list
uscale0b builds and applies a preconditioner for the conjugate
gradient induced dipole solver using a neighbor pair list
------------------------------------------------------------------------- */
void PairAmoeba::uscale0b(int mode, double **rsd, double **rsdp,
double **zrsd, double **zrsdp)
{
int i,j,itype,jtype,iclass,jclass,igroup,jgroup;
int ii,jj;
double xi,yi,zi;
double xr,yr,zr;
double r,r2,rr3,rr5;
double pdi,pti;
double polmin;
double poli,polik;
double alphai,alphak;
double damp,expdamp;
double pgamma;
double scale3,scale5;
double m1,m2,m3;
double m4,m5,m6;
double factor_uscale,factor_wscale;
double dmpik[5];
// owned atoms
double **x = atom->x;
int nlocal = atom->nlocal;
int nall = nlocal + atom->nghost;
// neighbor list info
int inum,jnum;
int *ilist,*jlist;
double *pclist;
inum = list->inum;
ilist = list->ilist;
// ------------------------------------------------
// apply the preconditioning matrix to the current residual
// ------------------------------------------------
if (mode == APPLY) {
// use diagonal preconditioner elements as first approximation
polmin = 0.00000001;
for (i = 0; i < nlocal; i++) {
itype = amtype[i];
poli = udiag * MAX(polmin,polarity[itype]);
for (j = 0; j < 3; j++) {
zrsd[i][j] = poli * rsd[i][j];
zrsdp[i][j] = poli * rsdp[i][j];
}
}
// zero zrsd,zrsdp for ghost atoms only
for (i = nlocal; i < nall; i++) {
for (j = 0; j < 3; j++) {
zrsd[i][j] = 0.0;
zrsdp[i][j] = 0.0;
}
}
// use the off-diagonal preconditioner elements in second phase
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
jlist = firstneigh_precond[i];
jnum = numneigh_precond[i];
pclist = firstneigh_pcpc[i];
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
j &= NEIGHMASK15;
m1 = pclist[0];
m2 = pclist[1];
m3 = pclist[2];
m4 = pclist[3];
m5 = pclist[4];
m6 = pclist[5];
zrsd[i][0] += m1*rsd[j][0] + m2*rsd[j][1] + m3*rsd[j][2];
zrsd[i][1] += m2*rsd[j][0] + m4*rsd[j][1] + m5*rsd[j][2];
zrsd[i][2] += m3*rsd[j][0] + m5*rsd[j][1] + m6*rsd[j][2];
zrsd[j][0] += m1*rsd[i][0] + m2*rsd[i][1] + m3*rsd[i][2];
zrsd[j][1] += m2*rsd[i][0] + m4*rsd[i][1] + m5*rsd[i][2];
zrsd[j][2] += m3*rsd[i][0] + m5*rsd[i][1] + m6*rsd[i][2];
zrsdp[i][0] += m1*rsdp[j][0] + m2*rsdp[j][1] + m3*rsdp[j][2];
zrsdp[i][1] += m2*rsdp[j][0] + m4*rsdp[j][1] + m5*rsdp[j][2];
zrsdp[i][2] += m3*rsdp[j][0] + m5*rsdp[j][1] + m6*rsdp[j][2];
zrsdp[j][0] += m1*rsdp[i][0] + m2*rsdp[i][1] + m3*rsdp[i][2];
zrsdp[j][1] += m2*rsdp[i][0] + m4*rsdp[i][1] + m5*rsdp[i][2];
zrsdp[j][2] += m3*rsdp[i][0] + m5*rsdp[i][1] + m6*rsdp[i][2];
pclist += 6;
}
}
return;
}
// ------------------------------------------------
// build the off-diagonal elements of preconditioning matrix
// ------------------------------------------------
dpage_pcpc->reset();
// determine the off-diagonal elements of the preconditioner
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
itype = amtype[i];
iclass = amtype2class[itype];
igroup = amgroup[i];
jlist = firstneigh_precond[i];
jnum = numneigh_precond[i];
xi = x[i][0];
yi = x[i][1];
zi = x[i][2];
poli = polarity[itype];
if (amoeba) {
pdi = pdamp[itype];
pti = thole[itype];
} else {
alphai = palpha[iclass];
}
// evaluate all sites in induce neigh list, no cutoff
// store results in plist for re-use in APPLY
pclist = dpage_pcpc->get(6*jnum);
firstneigh_pcpc[i] = pclist;
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
factor_wscale = special_polar_wscale[sbmask15(j)];
j &= NEIGHMASK15;
xr = x[j][0] - xi;
yr = x[j][1] - yi;
zr = x[j][2] - zi;
r2 = xr*xr + yr* yr + zr*zr;
r = sqrt(r2);
jtype = amtype[j];
jclass = amtype2class[jtype];
jgroup = amgroup[j];
if (igroup == jgroup) factor_uscale = polar_uscale;
else factor_uscale = 1.0;
if (amoeba) {
scale3 = factor_uscale;
scale5 = factor_uscale;
damp = pdi * pdamp[jtype];
if (damp != 0.0) {
pgamma = MIN(pti,thole[jtype]);
damp = -pgamma * cube(r/damp);
if (damp > -50.0) {
expdamp = exp(damp);
scale3 *= 1.0 - expdamp;
scale5 *= 1.0 - expdamp*(1.0-damp);
}
}
} else {
alphak = palpha[jclass];
dampmut(r,alphai,alphak,dmpik);
scale3 = factor_wscale * dmpik[2];
scale5 = factor_wscale * dmpik[4];
}
polik = poli * polarity[jtype];
rr3 = scale3 * polik / (r*r2);
rr5 = 3.0 * scale5 * polik / (r*r2*r2);
pclist[0] = rr5*xr*xr - rr3;
pclist[1] = rr5*xr*yr;
pclist[2] = rr5*xr*zr;
pclist[3] = rr5*yr*yr - rr3;
pclist[4] = rr5*yr*zr;
pclist[5] = rr5*zr*zr - rr3;
pclist += 6;
}
}
}
/* ----------------------------------------------------------------------
dfield0c = direct induction via Ewald sum
dfield0c computes the mutual electrostatic field due to
permanent multipole moments via Ewald summation
------------------------------------------------------------------------- */
void PairAmoeba::dfield0c(double **field, double **fieldp)
{
int i,j;
double term;
// zero out field,fieldp for owned and ghost atoms
int nlocal = atom->nlocal;
int nall = nlocal + atom->nghost;
for (i = 0; i < nall; i++) {
for (j = 0; j < 3; j++) {
field[i][j] = 0.0;
fieldp[i][j] = 0.0;
}
}
// get the reciprocal space part of the permanent field
double time0, time1, time2;
if (timer->has_sync()) MPI_Barrier(world);
time0 = platform::walltime();
if (polar_kspace_flag) udirect1(field);
time1 = platform::walltime();
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
fieldp[i][j] = field[i][j];
}
}
// get the real space portion of the permanent field
if (polar_rspace_flag) udirect2b(field,fieldp);
time2 = platform::walltime();
// get the self-energy portion of the permanent field
term = (4.0/3.0) * aewald*aewald*aewald / MY_PIS;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
field[i][j] += term*rpole[i][j+1];
fieldp[i][j] += term*rpole[i][j+1];
}
}
// accumulate timing information
time_direct_kspace += time1 - time0;
time_direct_rspace += time2 - time1;
}
/* ----------------------------------------------------------------------
umutual1 = Ewald recip mutual induced field
umutual1 computes the reciprocal space contribution of the
induced atomic dipole moments to the field
------------------------------------------------------------------------- */
void PairAmoeba::umutual1(double **field, double **fieldp)
{
int i,j,k,m,n;
int nxlo,nxhi,nylo,nyhi,nzlo,nzhi;
double term;
double a[3][3]; // indices not flipped vs Fortran
// return if the Ewald coefficient is zero
if (aewald < 1.0e-6) return;
// convert Cartesian dipoles to fractional coordinates
for (j = 0; j < 3; j++) {
a[0][j] = nfft1 * recip[0][j];
a[1][j] = nfft2 * recip[1][j];
a[2][j] = nfft3 * recip[2][j];
}
int nlocal = atom->nlocal;
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
fuind[i][j] = a[j][0]*uind[i][0] + a[j][1]*uind[i][1] + a[j][2]*uind[i][2];
fuinp[i][j] = a[j][0]*uinp[i][0] + a[j][1]*uinp[i][1] + a[j][2]*uinp[i][2];
}
}
double time0, time1;
// gridpre = my portion of 4d grid in brick decomp w/ ghost values
FFT_SCALAR ****gridpre = (FFT_SCALAR ****) ic_kspace->zero();
// map 2 values to grid
if (timer->has_sync()) MPI_Barrier(world);
time0 = platform::walltime();
grid_uind(fuind,fuinp,gridpre);
time1 = platform::walltime();
time_grid_uind += (time1 - time0);
// pre-convolution operations including forward FFT
// gridfft = my portion of complex 3d grid in FFT decomposition
FFT_SCALAR *gridfft = ic_kspace->pre_convolution();
// ---------------------
// convolution operation
// ---------------------
nxlo = ic_kspace->nxlo_fft;
nxhi = ic_kspace->nxhi_fft;
nylo = ic_kspace->nylo_fft;
nyhi = ic_kspace->nyhi_fft;
nzlo = ic_kspace->nzlo_fft;
nzhi = ic_kspace->nzhi_fft;
// use qfac values stored in udirect1()
m = n = 0;
for (k = nzlo; k <= nzhi; k++) {
for (j = nylo; j <= nyhi; j++) {
for (i = nxlo; i <= nxhi; i++) {
term = qfac[m++];
gridfft[n] *= term;
gridfft[n+1] *= term;
n += 2;
}
}
}
// post-convolution operations including backward FFT
// gridppost = my portion of 4d grid in brick decomp w/ ghost values
FFT_SCALAR ****gridpost = (FFT_SCALAR ****) ic_kspace->post_convolution();
// get potential
if (timer->has_sync()) MPI_Barrier(world);
time0 = platform::walltime();
fphi_uind(gridpost,fdip_phi1,fdip_phi2,fdip_sum_phi);
time1 = platform::walltime();
time_fphi_uind += (time1 - time0);
// store fractional reciprocal potentials for OPT method
if (poltyp == OPT) {
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 10; j++) {
fopt[i][optlevel][j] = fdip_phi1[i][j];
foptp[i][optlevel][j] = fdip_phi2[i][j];
}
}
}
// convert the dipole fields from fractional to Cartesian
for (i = 0; i < 3; i++) {
a[0][i] = nfft1 * recip[0][i];
a[1][i] = nfft2 * recip[1][i];
a[2][i] = nfft3 * recip[2][i];
}
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
dipfield1[i][j] = a[j][0]*fdip_phi1[i][1] +
a[j][1]*fdip_phi1[i][2] + a[j][2]*fdip_phi1[i][3];
dipfield2[i][j] = a[j][0]*fdip_phi2[i][1] +
a[j][1]*fdip_phi2[i][2] + a[j][2]*fdip_phi2[i][3];
}
}
// increment the field at each multipole site
for (i = 0; i < nlocal; i++) {
for (j = 0; j < 3; j++) {
field[i][j] -= dipfield1[i][j];
fieldp[i][j] -= dipfield2[i][j];
}
}
}
/* ----------------------------------------------------------------------
umutual2b = Ewald real mutual field via list
umutual2b computes the real space contribution of the induced
atomic dipole moments to the field via a neighbor list
------------------------------------------------------------------------- */
void PairAmoeba::umutual2b(double **field, double **fieldp)
{
int i,j,m,ii,jj,jnum;
double fid[3],fkd[3];
double fip[3],fkp[3];
double *uindi,*uindj,*uinpi,*uinpj;
// neigh list
int inum = list->inum;
int *ilist = list->ilist;
int *jlist;
double *tdipdip;
// loop over owned atoms and neighs
// compute field terms for each pairwise interaction
// using tdipdip values stored by udirect2b()
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
uindi = uind[i];
uinpi = uinp[i];
jlist = firstneigh_dipole[i];
tdipdip = firstneigh_dipdip[i];
jnum = numneigh_dipole[i];
for (jj = 0; jj < jnum; jj++) {
j = jlist[jj];
uindj = uind[j];
uinpj = uinp[j];
fid[0] = tdipdip[0]*uindj[0] + tdipdip[1]*uindj[1] + tdipdip[2]*uindj[2];
fid[1] = tdipdip[1]*uindj[0] + tdipdip[3]*uindj[1] + tdipdip[4]*uindj[2];
fid[2] = tdipdip[2]*uindj[0] + tdipdip[4]*uindj[1] + tdipdip[5]*uindj[2];
fkd[0] = tdipdip[0]*uindi[0] + tdipdip[1]*uindi[1] + tdipdip[2]*uindi[2];
fkd[1] = tdipdip[1]*uindi[0] + tdipdip[3]*uindi[1] + tdipdip[4]*uindi[2];
fkd[2] = tdipdip[2]*uindi[0] + tdipdip[4]*uindi[1] + tdipdip[5]*uindi[2];
fip[0] = tdipdip[0]*uinpj[0] + tdipdip[1]*uinpj[1] + tdipdip[2]*uinpj[2];
fip[1] = tdipdip[1]*uinpj[0] + tdipdip[3]*uinpj[1] + tdipdip[4]*uinpj[2];
fip[2] = tdipdip[2]*uinpj[0] + tdipdip[4]*uinpj[1] + tdipdip[5]*uinpj[2];
fkp[0] = tdipdip[0]*uinpi[0] + tdipdip[1]*uinpi[1] + tdipdip[2]*uinpi[2];
fkp[1] = tdipdip[1]*uinpi[0] + tdipdip[3]*uinpi[1] + tdipdip[4]*uinpi[2];
fkp[2] = tdipdip[2]*uinpi[0] + tdipdip[4]*uinpi[1] + tdipdip[5]*uinpi[2];
tdipdip += 6;
// increment the field at each site due to this interaction
for (m = 0; m < 3; m++) {
field[i][m] += fid[m];
field[j][m] += fkd[m];
fieldp[i][m] += fip[m];
fieldp[j][m] += fkp[m];
}
}
}
}
/* ----------------------------------------------------------------------
udirect1 = Ewald recip direct induced field
udirect1 computes the reciprocal space contribution of the
permanent atomic multipole moments to the field
since corresponding values in empole and epolar are different
------------------------------------------------------------------------- */
void PairAmoeba::udirect1(double **field)
{
int i,j,k,m,n;
int nhalf1,nhalf2,nhalf3;
int nxlo,nxhi,nylo,nyhi,nzlo,nzhi;
double r1,r2,r3;
double h1,h2,h3;
double volterm,denom;
double hsq,expterm;
double term,pterm;
// return if the Ewald coefficient is zero
if (aewald < 1.0e-6) return;
pterm = (MY_PI/aewald) * (MY_PI/aewald);
double volbox = domain->prd[0] * domain->prd[1] * domain->prd[2];
volterm = MY_PI * volbox;
// FFT moduli pre-computations
// set igrid for each atom and its B-spline coeffs
nfft1 = i_kspace->nx;
nfft2 = i_kspace->ny;
nfft3 = i_kspace->nz;
bsorder = i_kspace->order;
moduli();
bspline_fill();
// copy the multipole moments into local storage areas
int nlocal = atom->nlocal;
for (i = 0; i < nlocal; i++) {
cmp[i][0] = rpole[i][0];
cmp[i][1] = rpole[i][1];
cmp[i][2] = rpole[i][2];
cmp[i][3] = rpole[i][3];
cmp[i][4] = rpole[i][4];
cmp[i][5] = rpole[i][8];
cmp[i][6] = rpole[i][12];
cmp[i][7] = 2.0 * rpole[i][5];
cmp[i][8] = 2.0 * rpole[i][6];
cmp[i][9] = 2.0 * rpole[i][9];
}
// convert Cartesian multipoles to fractional coordinates
cmp_to_fmp(cmp,fmp);
// gridpre = my portion of 3d grid in brick decomp w/ ghost values
// zeroed by setup()
FFT_SCALAR ***gridpre = (FFT_SCALAR ***) i_kspace->zero();
// map multipole moments to grid
grid_mpole(fmp,gridpre);
// pre-convolution operations including forward FFT
// gridfft = my 1d portion of complex 3d grid in FFT decomp
FFT_SCALAR *gridfft = i_kspace->pre_convolution();
// ---------------------
// convolution operation
// ---------------------
nhalf1 = (nfft1+1) / 2;
nhalf2 = (nfft2+1) / 2;
nhalf3 = (nfft3+1) / 2;
nxlo = i_kspace->nxlo_fft;
nxhi = i_kspace->nxhi_fft;
nylo = i_kspace->nylo_fft;
nyhi = i_kspace->nyhi_fft;
nzlo = i_kspace->nzlo_fft;
nzhi = i_kspace->nzhi_fft;
m = n = 0;
for (k = nzlo; k <= nzhi; k++) {
for (j = nylo; j <= nyhi; j++) {
for (i = nxlo; i <= nxhi; i++) {
r1 = (i >= nhalf1) ? i-nfft1 : i;
r2 = (j >= nhalf2) ? j-nfft2 : j;
r3 = (k >= nhalf3) ? k-nfft3 : k;
h1 = recip[0][0]*r1 + recip[0][1]*r2 + recip[0][2]*r3; // matvec
h2 = recip[1][0]*r1 + recip[1][1]*r2 + recip[1][2]*r3;
h3 = recip[2][0]*r1 + recip[2][1]*r2 + recip[2][2]*r3;
hsq = h1*h1 + h2*h2 + h3*h3;
term = -pterm * hsq;
expterm = 0.0;
if (term > -50.0 && hsq != 0.0) {
denom = volterm*hsq*bsmod1[i]*bsmod2[j]*bsmod3[k];
expterm = exp(term) / denom;
}
qfac[m++] = expterm;
gridfft[n] *= expterm;
gridfft[n+1] *= expterm;
n += 2;
}
}
}
// post-convolution operations including backward FFT
// gridppost = my portion of 3d grid in brick decomp w/ ghost values
FFT_SCALAR ***gridpost = (FFT_SCALAR ***) i_kspace->post_convolution();
// get potential
fphi_mpole(gridpost,fphi);
// convert the field from fractional to Cartesian
fphi_to_cphi(fphi,cphi);
// increment the field at each multipole site
for (i = 0; i < nlocal; i++) {
field[i][0] -= cphi[i][1];
field[i][1] -= cphi[i][2];
field[i][2] -= cphi[i][3];
}
}
/* ----------------------------------------------------------------------
udirect2b = Ewald real direct field via list
udirect2b computes the real space contribution of the permanent
atomic multipole moments to the field via a neighbor list
------------------------------------------------------------------------- */
void PairAmoeba::udirect2b(double **field, double **fieldp)
{
int i,j,m,n,ii,jj,jextra,ndip,itype,jtype,iclass,jclass,igroup,jgroup;
double xr,yr,zr,r,r2;
double rr1,rr2,rr3;
double rr5,rr7;
double rr3i,rr5i,rr7i;
double rr3k,rr5k,rr7k;
double rr3ik,rr5ik;
double bfac,exp2a;
double ci,dix,diy,diz;
double qixx,qiyy,qizz;
double qixy,qixz,qiyz;
double ck,dkx,dky,dkz;
double qkxx,qkyy,qkzz;
double qkxy,qkxz,qkyz;
double dir,dkr;
double qix,qiy,qiz,qir;
double qkx,qky,qkz,qkr;
double corei,corek;
double vali,valk;
double alphai,alphak;
double ralpha,aefac;
double aesq2,aesq2n;
double pdi,pti,ddi;
double pgamma;
double damp,expdamp;
double scale3,scale5;
double scale7,scalek;
double bn[4],bcn[3];
double fid[3],fkd[3];
double fip[3],fkp[3];
double dmpi[7],dmpk[7];
double dmpik[5];
double factor_dscale,factor_pscale,factor_uscale,factor_wscale;
int inum,jnum;
int *ilist,*jlist,*numneigh,**firstneigh;
// owned atoms
double **x = atom->x;
double *pval = atom->dvector[index_pval];
// neigh list
inum = list->inum;
ilist = list->ilist;
numneigh = list->numneigh;
firstneigh = list->firstneigh;
aesq2 = 2.0 * aewald * aewald;
aesq2n = 0.0;
if (aewald > 0.0) aesq2n = 1.0 / (MY_PIS*aewald);
// rebuild dipole-dipole pair list and store pairwise dipole matrices
// done one atom at a time in real-space double loop over atoms & neighs
int *neighptr;
double *tdipdip;
// compute the real space portion of the Ewald summation
ipage_dipole->reset();
dpage_dipdip->reset();
for (ii = 0; ii < inum; ii++) {
i = ilist[ii];
itype = amtype[i];
iclass = amtype2class[itype];
igroup = amgroup[i];
jlist = firstneigh[i];
jnum = numneigh[i];
n = ndip = 0;
neighptr = ipage_dipole->vget();
tdipdip = dpage_dipdip->vget();
ci = rpole[i][0];
dix = rpole[i][1];
diy = rpole[i][2];
diz = rpole[i][3];
qixx = rpole[i][4];
qixy = rpole[i][5];
qixz = rpole[i][6];
qiyy = rpole[i][8];
qiyz = rpole[i][9];
qizz = rpole[i][12];
if (amoeba) {
pdi = pdamp[itype];
pti = thole[itype];
ddi = dirdamp[itype];
} else {
corei = pcore[iclass];
alphai = palpha[iclass];
vali = pval[i];
}
// evaluate all sites within the cutoff distance
for (jj = 0; jj < jnum; jj++) {
jextra = jlist[jj];
j = jextra & NEIGHMASK15;
xr = x[j][0] - x[i][0];
yr = x[j][1] - x[i][1];
zr = x[j][2] - x[i][2];
r2 = xr*xr + yr* yr + zr*zr;
if (r2 > off2) continue;
jtype = amtype[j];
jclass = amtype2class[jtype];
jgroup = amgroup[j];
if (amoeba) {
factor_wscale = special_polar_wscale[sbmask15(jextra)];
if (igroup == jgroup) {
factor_pscale = special_polar_piscale[sbmask15(jextra)];
factor_dscale = polar_dscale;
factor_uscale = polar_uscale;
} else {
factor_pscale = special_polar_pscale[sbmask15(jextra)];
factor_dscale = factor_uscale = 1.0;
}
} else {
factor_wscale = special_polar_wscale[sbmask15(jextra)];
if (igroup == jgroup) {
factor_dscale = factor_pscale = special_polar_piscale[sbmask15(jextra)];
factor_uscale = polar_uscale;
} else {
factor_dscale = factor_pscale = special_polar_pscale[sbmask15(jextra)];
factor_uscale = 1.0;
}
}
r = sqrt(r2);
rr1 = 1.0 / r;
rr2 = rr1 * rr1;
rr3 = rr2 * rr1;
rr5 = 3.0 * rr2 * rr3;
rr7 = 5.0 * rr2 * rr5;
ck = rpole[j][0];
dkx = rpole[j][1];
dky = rpole[j][2];
dkz = rpole[j][3];
qkxx = rpole[j][4];
qkxy = rpole[j][5];
qkxz = rpole[j][6];
qkyy = rpole[j][8];
qkyz = rpole[j][9];
qkzz = rpole[j][12];
// intermediates involving moments and separation distance
dir = dix*xr + diy*yr + diz*zr;
qix = qixx*xr + qixy*yr + qixz*zr;
qiy = qixy*xr + qiyy*yr + qiyz*zr;
qiz = qixz*xr + qiyz*yr + qizz*zr;
qir = qix*xr + qiy*yr + qiz*zr;
dkr = dkx*xr + dky*yr + dkz*zr;
qkx = qkxx*xr + qkxy*yr + qkxz*zr;
qky = qkxy*xr + qkyy*yr + qkyz*zr;
qkz = qkxz*xr + qkyz*yr + qkzz*zr;
qkr = qkx*xr + qky*yr + qkz*zr;
// calculate the real space Ewald error function terms
ralpha = aewald * r;
bn[0] = erfc(ralpha) * rr1;
exp2a = exp(-ralpha*ralpha);
aefac = aesq2n;
for (m = 1; m <= 3; m++) {
bfac = m+m-1;
aefac = aesq2 * aefac;
bn[m] = (bfac*bn[m-1]+aefac*exp2a) * rr2;
}
// find the field components for Thole polarization damping
if (amoeba) {
scale3 = 1.0;
scale5 = 1.0;
scale7 = 1.0;
damp = pdi * pdamp[jtype];
if (damp != 0.0) {
pgamma = MIN(ddi,dirdamp[jtype]);
if (pgamma != 0.0) {
damp = pgamma * pow(r/damp,1.5);
if (damp < 50.0) {
expdamp = exp(-damp) ;
scale3 = 1.0 - expdamp ;
scale5 = 1.0 - expdamp*(1.0+0.5*damp);
scale7 = 1.0 - expdamp*(1.0+0.65*damp + 0.15*damp*damp);
}
} else {
pgamma = MIN(pti,thole[jtype]);
damp = pgamma * cube(r/damp);
if (damp < 50.0) {
expdamp = exp(-damp);
scale3 = 1.0 - expdamp;
scale5 = 1.0 - expdamp*(1.0+damp);
scale7 = 1.0 - expdamp*(1.0+damp + 0.6*damp*damp);
}
}
}
scalek = factor_dscale;
bcn[0] = bn[1] - (1.0-scalek*scale3)*rr3;
bcn[1] = bn[2] - (1.0-scalek*scale5)*rr5;
bcn[2] = bn[3] - (1.0-scalek*scale7)*rr7;
fid[0] = -xr*(bcn[0]*ck-bcn[1]*dkr+bcn[2]*qkr) -
bcn[0]*dkx + 2.0*bcn[1]*qkx;
fid[1] = -yr*(bcn[0]*ck-bcn[1]*dkr+bcn[2]*qkr) -
bcn[0]*dky + 2.0*bcn[1]*qky;
fid[2] = -zr*(bcn[0]*ck-bcn[1]*dkr+bcn[2]*qkr) -
bcn[0]*dkz + 2.0*bcn[1]*qkz;
fkd[0] = xr*(bcn[0]*ci+bcn[1]*dir+bcn[2]*qir) -
bcn[0]*dix - 2.0*bcn[1]*qix;
fkd[1] = yr*(bcn[0]*ci+bcn[1]*dir+bcn[2]*qir) -
bcn[0]*diy - 2.0*bcn[1]*qiy;
fkd[2] = zr*(bcn[0]*ci+bcn[1]*dir+bcn[2]*qir) -
bcn[0]*diz - 2.0*bcn[1]*qiz;
scalek = factor_pscale;
bcn[0] = bn[1] - (1.0-scalek*scale3)*rr3;
bcn[1] = bn[2] - (1.0-scalek*scale5)*rr5;
bcn[2] = bn[3] - (1.0-scalek*scale7)*rr7;
fip[0] = -xr*(bcn[0]*ck-bcn[1]*dkr+bcn[2]*qkr) -
bcn[0]*dkx + 2.0*bcn[1]*qkx;
fip[1] = -yr*(bcn[0]*ck-bcn[1]*dkr+bcn[2]*qkr) -
bcn[0]*dky + 2.0*bcn[1]*qky;
fip[2] = -zr*(bcn[0]*ck-bcn[1]*dkr+bcn[2]*qkr) -
bcn[0]*dkz + 2.0*bcn[1]*qkz;
fkp[0] = xr*(bcn[0]*ci+bcn[1]*dir+bcn[2]*qir) -
bcn[0]*dix - 2.0*bcn[1]*qix;
fkp[1] = yr*(bcn[0]*ci+bcn[1]*dir+bcn[2]*qir) -
bcn[0]*diy - 2.0*bcn[1]*qiy;
fkp[2] = zr*(bcn[0]*ci+bcn[1]*dir+bcn[2]*qir) -
bcn[0]*diz - 2.0*bcn[1]*qiz;
// find terms needed later to compute mutual polarization
if (poltyp != DIRECT) {
scale3 = 1.0;
scale5 = 1.0;
damp = pdi * pdamp[jtype];
if (damp != 0.0) {
pgamma = MIN(pti,thole[jtype]);
damp = pgamma * cube(r/damp);
if (damp < 50.0) {
expdamp = exp(-damp);
scale3 = 1.0 - expdamp;
scale5 = 1.0 - expdamp*(1.0+damp);
}
}
scalek = factor_uscale;
bcn[0] = bn[1] - (1.0-scalek*scale3)*rr3;
bcn[1] = bn[2] - (1.0-scalek*scale5)*rr5;
neighptr[n++] = j;
tdipdip[ndip++] = -bcn[0] + bcn[1]*xr*xr;
tdipdip[ndip++] = bcn[1]*xr*yr;
tdipdip[ndip++] = bcn[1]*xr*zr;
tdipdip[ndip++] = -bcn[0] + bcn[1]*yr*yr;
tdipdip[ndip++] = bcn[1]*yr*zr;
tdipdip[ndip++] = -bcn[0] + bcn[1]*zr*zr;
}
// find the field components for charge penetration damping
} else {
corek = pcore[jclass];
alphak = palpha[jclass];
valk = pval[j];
dampdir(r,alphai,alphak,dmpi,dmpk);
scalek = factor_dscale;
rr3i = bn[1] - (1.0-scalek*dmpi[2])*rr3;
rr5i = bn[2] - (1.0-scalek*dmpi[4])*rr5;
rr7i = bn[3] - (1.0-scalek*dmpi[6])*rr7;
rr3k = bn[1] - (1.0-scalek*dmpk[2])*rr3;
rr5k = bn[2] - (1.0-scalek*dmpk[4])*rr5;
rr7k = bn[3] - (1.0-scalek*dmpk[6])*rr7;
rr3 = bn[1] - (1.0-scalek)*rr3;
fid[0] = -xr*(rr3*corek + rr3k*valk - rr5k*dkr + rr7k*qkr) -
rr3k*dkx + 2.0*rr5k*qkx;
fid[1] = -yr*(rr3*corek + rr3k*valk - rr5k*dkr + rr7k*qkr) -
rr3k*dky + 2.0*rr5k*qky;
fid[2] = -zr*(rr3*corek + rr3k*valk - rr5k*dkr + rr7k*qkr) -
rr3k*dkz + 2.0*rr5k*qkz;
fkd[0] = xr*(rr3*corei + rr3i*vali + rr5i*dir + rr7i*qir) -
rr3i*dix - 2.0*rr5i*qix;
fkd[1] = yr*(rr3*corei + rr3i*vali + rr5i*dir + rr7i*qir) -
rr3i*diy - 2.0*rr5i*qiy;
fkd[2] = zr*(rr3*corei + rr3i*vali + rr5i*dir + rr7i*qir) -
rr3i*diz - 2.0*rr5i*qiz;
scalek = factor_pscale;
rr3 = rr2 * rr1;
rr3i = bn[1] - (1.0-scalek*dmpi[2])*rr3;
rr5i = bn[2] - (1.0-scalek*dmpi[4])*rr5;
rr7i = bn[3] - (1.0-scalek*dmpi[6])*rr7;
rr3k = bn[1] - (1.0-scalek*dmpk[2])*rr3;
rr5k = bn[2] - (1.0-scalek*dmpk[4])*rr5;
rr7k = bn[3] - (1.0-scalek*dmpk[6])*rr7;
rr3 = bn[1] - (1.0-scalek)*rr3;
fip[0] = -xr*(rr3*corek + rr3k*valk - rr5k*dkr + rr7k*qkr) -
rr3k*dkx + 2.0*rr5k*qkx;
fip[1] = -yr*(rr3*corek + rr3k*valk - rr5k*dkr + rr7k*qkr) -
rr3k*dky + 2.0*rr5k*qky;
fip[2] = -zr*(rr3*corek + rr3k*valk - rr5k*dkr + rr7k*qkr) -
rr3k*dkz + 2.0*rr5k*qkz;
fkp[0] = xr*(rr3*corei + rr3i*vali + rr5i*dir + rr7i*qir) -
rr3i*dix - 2.0*rr5i*qix;
fkp[1] = yr*(rr3*corei + rr3i*vali + rr5i*dir + rr7i*qir) -
rr3i*diy - 2.0*rr5i*qiy;
fkp[2] = zr*(rr3*corei + rr3i*vali + rr5i*dir + rr7i*qir) -
rr3i*diz - 2.0*rr5i*qiz;
// find terms needed later to compute mutual polarization
if (poltyp != DIRECT) {
dampmut(r,alphai,alphak,dmpik);
scalek = factor_wscale;
rr3 = rr2 * rr1;
rr3ik = bn[1] - (1.0-scalek*dmpik[2])*rr3;
rr5ik = bn[2] - (1.0-scalek*dmpik[4])*rr5;
neighptr[n++] = j;
tdipdip[ndip++] = -rr3ik + rr5ik*xr*xr;
tdipdip[ndip++] = rr5ik*xr*yr;
tdipdip[ndip++] = rr5ik*xr*zr;
tdipdip[ndip++] = -rr3ik + rr5ik*yr*yr;
tdipdip[ndip++] = rr5ik*yr*zr;
tdipdip[ndip++] = -rr3ik + rr5ik*zr*zr;
}
}
// increment the field at each site due to this interaction
for (m = 0; m < 3; m++) {
field[i][m] += fid[m];
field[j][m] += fkd[m];
fieldp[i][m] += fip[m];
fieldp[j][m] += fkp[m];
}
}
firstneigh_dipole[i] = neighptr;
firstneigh_dipdip[i] = tdipdip;
numneigh_dipole[i] = n;
ipage_dipole->vgot(n);
dpage_dipdip->vgot(ndip);
}
}
/* ----------------------------------------------------------------------
dampmut = mutual field damping coefficents
dampmut generates coefficients for the mutual field damping
function for powers of the interatomic distance
------------------------------------------------------------------------- */
void PairAmoeba::dampmut(double r, double alphai, double alphak, double *dmpik)
{
double termi,termk;
double termi2,termk2;
double alphai2,alphak2;
double eps,diff;
double expi,expk;
double dampi,dampk;
double dampi2,dampi3;
double dampi4,dampi5;
double dampk2,dampk3;
// compute tolerance and exponential damping factors
eps = 0.001;
diff = fabs(alphai-alphak);
dampi = alphai * r;
dampk = alphak * r;
expi = exp(-dampi);
expk = exp(-dampk);
// valence-valence charge penetration damping for Gordon f1 (HIPPO)
dampi2 = dampi * dampi;
dampi3 = dampi * dampi2;
if (diff < eps) {
dampi4 = dampi2 * dampi2;
dampi5 = dampi2 * dampi3;
dmpik[2] = 1.0 - (1.0 + dampi + 0.5*dampi2 +
7.0*dampi3/48.0 + dampi4/48.0)*expi;
dmpik[4] = 1.0 - (1.0 + dampi + 0.5*dampi2 + dampi3/6.0 +
dampi4/24.0 + dampi5/144.0)*expi;
} else {
dampk2 = dampk * dampk;
dampk3 = dampk * dampk2;
alphai2 = alphai * alphai;
alphak2 = alphak * alphak;
termi = alphak2 / (alphak2-alphai2);
termk = alphai2 / (alphai2-alphak2);
termi2 = termi * termi;
termk2 = termk * termk;
dmpik[2] = 1.0 - termi2*(1.0+dampi+0.5*dampi2)*expi -
termk2*(1.0+dampk+0.5*dampk2)*expk -
2.0*termi2*termk*(1.0+dampi)*expi - 2.0*termk2*termi*(1.0+dampk)*expk;
dmpik[4] = 1.0 - termi2*(1.0+dampi+0.5*dampi2 + dampi3/6.0)*expi -
termk2*(1.0+dampk+0.5*dampk2 + dampk3/6.00)*expk -
2.0*termi2*termk *(1.0+dampi+dampi2/3.0)*expi -
2.0*termk2*termi *(1.0+dampk+dampk2/3.0)*expk;
}
}
/* ----------------------------------------------------------------------
dampdir = direct field damping coefficents
dampdir generates coefficients for the direct field damping
function for powers of the interatomic distance
------------------------------------------------------------------------- */
void PairAmoeba::dampdir(double r, double alphai, double alphak,
double *dmpi, double *dmpk)
{
double eps,diff;
double expi,expk;
double dampi,dampk;
double dampi2,dampk2;
double dampi3,dampk3;
double dampi4,dampk4;
// compute tolerance and exponential damping factors
eps = 0.001;
diff = fabs(alphai-alphak);
dampi = alphai * r;
dampk = alphak * r;
expi = exp(-dampi);
expk = exp(-dampk);
// core-valence charge penetration damping for Gordon f1 (HIPPO)
dampi2 = dampi * dampi;
dampi3 = dampi * dampi2;
dampi4 = dampi2 * dampi2;
dmpi[2] = 1.0 - (1.0 + dampi + 0.5*dampi2)*expi;
dmpi[4] = 1.0 - (1.0 + dampi + 0.5*dampi2 + dampi3/6.0)*expi;
dmpi[6] = 1.0 - (1.0 + dampi + 0.5*dampi2 + dampi3/6.0 + dampi4/30.0)*expi;
if (diff < eps) {
dmpk[2] = dmpi[2];
dmpk[4] = dmpi[4];
dmpk[6] = dmpi[6];
} else {
dampk2 = dampk * dampk;
dampk3 = dampk * dampk2;
dampk4 = dampk2 * dampk2;
dmpk[2] = 1.0 - (1.0 + dampk + 0.5*dampk2)*expk;
dmpk[4] = 1.0 - (1.0 + dampk + 0.5*dampk2 + dampk3/6.0)*expk;
dmpk[6] = 1.0 - (1.0 + dampk + 0.5*dampk2 + dampk3/6.0 + dampk4/30.0)*expk;
}
}
/* ----------------------------------------------------------------------
cholesky = modified Cholesky linear solver
cholesky uses a modified Cholesky method to solve the linear
system Ax = b, returning "x" in "b"; "A" is a real symmetric
positive definite matrix with its upper triangle (including the
diagonal) stored by rows
literature reference:
R. S. Martin, G. Peters and J. H. Wilkinson, "Symmetric
Decomposition of a Positive Definite Matrix", Numerische
Mathematik, 7, 362-383 (1965)
------------------------------------------------------------------------- */
void PairAmoeba::cholesky(int nvar, double *a, double *b)
{
int i,j,k;
int ii,ij,ik,ki,kk;
int im,jk,jm;
double r,s,t;
// all code in this method is exact translation from Fortran version
// decrement pointers so can access vectors like Fortran does from 1:N
a--;
b--;
// Cholesky factorization to reduce A to (L)(D)(L transpose)
// L has a unit diagonal; store 1.0/D on the diagonal of A
ii = 1;
for (i = 1; i <= nvar; i++) {
im = i - 1;
if (i != 1) {
ij = i;
for (j = 1; j <= im; j++) {
r = a[ij];
if (j != 1) {
ik = i;
jk = j;
jm = j - 1;
for (k = 1; k <= jm; k++) {
r = r - a[ik]*a[jk];
ik = nvar - k + ik;
jk = nvar - k + jk;
}
}
a[ij] = r;
ij = nvar - j + ij;
}
}
r = a[ii];
if (i != 1) {
kk = 1;
ik = i;
for (k = 1; k <= im; k++) {
s = a[ik];
t = s * a[kk];
a[ik] = t;
r = r - s*t;
ik = nvar - k + ik;
kk = nvar - k + 1 + kk;
}
}
a[ii] = 1.0 / r;
ii = nvar - i + 1 + ii;
}
// solve linear equations; first solve Ly = b for y
for (i = 1; i <= nvar; i++) {
if (i != 1) {
ik = i;
im = i - 1;
r = b[i];
for (k = 1; k <= im; k++) {
r = r - b[k]*a[ik];
ik = nvar - k + ik;
}
b[i] = r;
}
}
// finally, solve (D)(L transpose)(x) = y for x
ii = nvar*(nvar+1)/2;
for (j = 1; j <= nvar; j++) {
i = nvar + 1 - j;
r = b[i] * a[ii];
if (j != 1) {
im = i + 1;
ki = ii + 1;
for (k = im; k <= nvar; k++) {
r = r - a[ki]*b[k];
ki = ki + 1;
}
}
b[i] = r;
ii = ii - j - 1;
}
}