CC-RSP and EOM-CC expectation-value 9 frameworks have also been developed for computing valence 2PA cross sections; the latter employing first-order response wave functions to compute the EOM-CC-parameterized exact sum-over-states expressions for the 2PA moments. Within the EOM-CC framework, implementations based on damped response theory also exist (unreported 64 ), which compute complex-valued 2PA moments following the introduction of the phenomenological damping for avoiding divergences in modeling doubly resonant 2PA processes. However, the extension of the EOM-CC strategies for modeling valence 2PA to X2PA is not straightforward.