guess_symmetries

adcc.guess_symmetries(matrix, irrep='A', spin_change=0, spin_block_symmetrisation='none')

Return guess symmetry objects (one for each AmplitudeVector block) such that the specified requirements on the guesses are satisfied.

matrix The matrix for which guesses are to be constructed irrep String describing the irreducable representation to consider. spin_change The spin change to enforce in an excitation.

Typical values are 0 (singlet/triplet/any) and -1 (spin-flip).

spin_block_symmetrisation

Symmetrisation to enforce between equivalent spin blocks, which all yield the desired spin_change. E.g. if spin_change == 0, then both the alpha->alpha and beta->beta blocks of the singles part of the excitation vector achieve a spin change of 0. The symmetry specified with this parameter will then be imposed between the a-a and b-b blocks. Valid values are “none”, “symmetric” and “antisymmetric”, where “none” enforces no particular symmetry.