triqs.operators.util.extractors.extract_U_dict4

triqs.operators.util.extractors.extract_U_dict4()

Signature : (many_body_operator H, bool ignore_irrelevant = false) -> dict4_t<real_or_complex>

Extract U-matrix of the interaction part \(\frac{1}{2}\sum_{ijkl} U_{ijkl} c^\dagger_i c^\dagger_j c_l c_k\) from a Hamiltonian H as a 4-index dictionary.

Parameters:

• H (Operator) – The Hamiltonian.

• ignore_irrelevant (bool) – If True, ignore all irrelevant terms in H. Otherwise raise an exception when such terms are met.

Returns:

U_dict – The 4-index interaction dictionary, {(i,j,k,l) : float}.

Return type:

dict