Function uw12::three_el::calculate_direct_energy

• Defined in File direct_utils.hpp

Function Documentation

double uw12::three_el::calculate_direct_energy(const utils::MatVec &x, const utils::MatVec &ttilde, double scale_opp_spin, double scale_same_spin)

Calculates the direct three-el energy.

Direct three-el energy is given by:

\[E_c^{3el, +} = \sum_{\sigma} \sum_{AB} X_{AB}^{\sigma} \tilde{t}_{AB}^{\sigma} \]

for matrices \(X_{AB}^{\sigma}\) and \(\tilde{t}_{AB}^{\sigma}\).

Parameters

• x – Matrices \(X_{AB}^{\sigma}\)

• ttilde – Matrices \(\tilde{t}_{AB}^{\sigma}\)

• scale_opp_spin – Opposite-spin scale factor \(\kappa_0\)

• scale_same_spin – Same-spin scale factor \(\kappa_1\)

Returns

Direct three-el energy