The EOM-EE-CCSD calculations also yield a set of states that do not have counterparts among the EOM-EA-CCSD states. As anticipated, the EOM-EE-CCSD method yields excited states derived by promoting electrons localized on the AB moiety. These states can be classified as AB-like states of π → π * type. One of the new states should again be characterized as a state of a mixed character as it derives from the π → s(Ca) transition. Some of the AB-like states (especially quartets) show high spin-contamination, which indicates that their proper description would require inclusion of higher terms in the EOM-CC expansion (see Fig. and the corresponding discussion in Ref. 92). Fig. highlights the differences between EOM-EA-CCSD and EOM-EE-CCSD results.