double HeliumJastrowAnalytical::localEnergy(const mat &r, VMCSolver *solver)
{
double localEnergy1 = 0;
double localEnergy2 = 0;
//Grabbing all the necessary constants stored in the solver
double charge = solver->getCharge();
double alpha = solver->getAlpha();
double beta = solver->getBeta();
//Precalculating the distances
double r1 = norm(r.row(0));
double r2 = norm(r.row(1));
double r12 = norm(r.row(0) - r.row(1));
//The part of the local Energy that was the same as for the first simple case
localEnergy1 = (alpha - charge)*(1./r1+1./r2) + 1./(r12) - pow(alpha,2);
//The second contribution to the local Energy, I think there is an error here
localEnergy2 = 0.5*pow((1+beta*r12),-2) * (alpha*(r1+r2)/r12 * (1. - norm_dot(r.row(0),r.row(1))) -
0.5*pow((1+beta*r12),-2) - 2./r12 + 2.*beta/(1 + beta * r12) );
// cout << endl << "In JastrowAnalytical" << endl;
// cout << "LocalEnergy1 is " <<localEnergy1 << endl;
// cout << "LocalEnergy2 is " <<localEnergy2 << endl;
return localEnergy1 + localEnergy2;
}
/*! Angle \theta between \p a and \p b.
* \see https://en.wikipedia.org/wiki/Dot_product#Geometric_interpretation */
template<class C> inline pure typename C::value_type angle(const C& a,
const C& b) {
return std::acos(norm_dot(a, b));
}