double_factorized_t2_alpha_beta

double_factorized_t2_alpha_beta(t2_amplitudes, tol, max_terms=None)

Double-factorized decomposition of alpha-beta (spin-unrestricted) $t_2$ amplitudes.

Returns a list of terms suitable for reconstruction by reconstruct_t2_alpha_beta(). The number of terms is truncated to max_terms (default: all).

Parameters

• t2_amplitudes – the alpha-beta $t_2$ amplitudes of shape (nocc_a, nocc_b, nvrt_a, nvrt_b).
• tol – the tolerance controlling the truncation error of the decomposition.
• max_terms – the maximum number of terms to retain. Defaults to all.

Returns

A list of 2-tuples, each consisting of

• a 3-tuple of the diagonal Coulomb matrices in the order (aa, ab, bb)
• a 2-tuple of the orbital rotations in the order (alpha, beta)