ArrayXd operator()(Array1D En, Array2D psi) {
using scalar_t = typename Array1D::Scalar;
auto const scale = 1 / (broadening * sqrt(2 * constant::pi));
auto const constant = -0.5f / pow(broadening, 2);
// DOS(r) = 1 / (b * sqrt(2pi)) * sum(|psi(r)|^2 * exp(-0.5 * (En-E)^2 / b^2))
ArrayXd ldos(psi.rows());
for (auto i = 0; i < ldos.size(); ++i) {
ArrayX<scalar_t> psi2 = psi.row(i).abs2();
auto gaussian = exp((En - target_energy).square() * constant);
ldos[i] = scale * sum(psi2 * gaussian);
}
return ldos;
}
