void ComputeForces ()
{
VecR dr;
real fcVal, rr, rrCut, rri, rri3;
int j1, j2, n;
rrCut = Sqr (rCut);
DO_MOL VZero (mol[n].ra);
uSum = 0.;
virSum = 0.;
for (j1 = 0; j1 < nMol - 1; j1 ++) {
for (j2 = j1 + 1; j2 < nMol; j2 ++) {
VSub (dr, mol[j1].r, mol[j2].r);
VWrapAll (dr);
rr = VLenSq (dr);
if (rr < rrCut) {
rri = 1. / rr;
rri3 = Cube (rri);
fcVal = 48. * rri3 * (rri3 - 0.5) * rri;
VVSAdd (mol[j1].ra, fcVal, dr);
VVSAdd (mol[j2].ra, - fcVal, dr);
uSum += 4. * rri3 * (rri3 - 1.) + 1.;
virSum += fcVal * rr;
}
}
}
}
void EvalRdf ()
{
VecR dr;
real deltaR, normFac, rr, sr1, sr2, ss;
int j1, j2, k, n;
if (countRdf == 0) {
for (k = 0; k < 3; k ++) {
for (n = 0; n < sizeHistRdf; n ++) histRdf[k][n] = 0.;
}
}
deltaR = rangeRdf / sizeHistRdf;
for (j1 = 0; j1 < nMol - 1; j1 ++) {
for (j2 = j1 + 1; j2 < nMol; j2 ++) {
VSub (dr, mol[j1].r, mol[j2].r);
VWrapAll (dr);
rr = VLenSq (dr);
if (rr < Sqr (rangeRdf)) {
ss = VDot (mol[j1].s, mol[j2].s);
sr1 = VDot (mol[j1].s, dr);
sr2 = VDot (mol[j2].s, dr);
n = sqrt (rr) / deltaR;
++ histRdf[0][n];
histRdf[1][n] += ss;
histRdf[2][n] += 3. * sr1 * sr2 / rr - ss;
}
}
}
++ countRdf;
if (countRdf == limitRdf) {
normFac = VProd (region) / (2. * M_PI * Cube (deltaR) *
Sqr (nMol) * countRdf);
for (k = 0; k < 3; k ++) {
for (n = 0; n < sizeHistRdf; n ++)
histRdf[k][n] *= normFac / Sqr (n - 0.5);
}
PrintRdf (stdout);
countRdf = 0;
}
}
void ComputeForcesDipoleR ()
{
VecR dr, w;
real a1, a2, a3, alpha2, d, irPi, rr, rrCut, rri, sr1, sr2, ss, t;
int j1, j2, n;
rrCut = Sqr (0.5 * region.x);
irPi = 1. / sqrt (M_PI);
alpha2 = Sqr (alpha);
DO_MOL VZero (mol[n].sa);
for (j1 = 0; j1 < nMol - 1; j1 ++) {
for (j2 = j1 + 1; j2 < nMol; j2 ++) {
VSub (dr, mol[j1].r, mol[j2].r);
VWrapAll (dr);
rr = VLenSq (dr);
if (rr < rrCut) {
d = sqrt (rr);
rri = 1. / rr;
t = 2. * dipoleInt * alpha * exp (- alpha2 * rr) * rri * irPi;
a1 = dipoleInt * erfc (alpha * d) * rri / d + t;
a2 = 3. * a1 * rri + 2. * alpha2 * t;
a3 = 5. * a2 * rri + 4. * Sqr (alpha2) * t;
ss = VDot (mol[j1].s, mol[j2].s);
sr1 = VDot (mol[j1].s, dr);
sr2 = VDot (mol[j2].s, dr);
VSSAdd (w, sr2, mol[j1].s, sr1, mol[j2].s);
t = (a2 * ss - a3 * sr1 * sr2);
VSSAdd (w, t, dr, a2, w);
VVAdd (mol[j1].ra, w);
VVSub (mol[j2].ra, w);
VVSAdd (mol[j1].sa, - a1, mol[j2].s);
VVSAdd (mol[j1].sa, a2 * sr2, dr);
VVSAdd (mol[j2].sa, - a1, mol[j1].s);
VVSAdd (mol[j2].sa, a2 * sr1, dr);
uSum += a1 * ss - a2 * sr1 * sr2;
}
}
}
uSum -= 2. * dipoleInt * Cube (alpha) * nMol * irPi / 3.;
}
