reconstruct_t2

reconstruct_t2(terms, nocc)

Reconstructs spin-restricted $t_2$ amplitudes from a double-factorized decomposition.

Computes $i \sum_k \sum_{pq} Z^{(k)}_{pq} U^{(k)}_{ap} U^{(k)*}_{ip} U^{(k)}_{bq} U^{(k)*}_{jq}$ and slices to the occupied/virtual block [:nocc, :nocc, nocc:, nocc:].

Parameters

• terms – the list of $(Z, U)$ 2-tuples produced by double_factorized_t2().
• nocc – the number of occupied orbitals.

Returns

The reconstructed $t_2$ amplitudes of shape (nocc, nocc, nvrt, nvrt).