One of these proposed solutions is based on the use of the Frozen-Density Embedding (FDE) formalism and allows to effectively avoid the spin-density overdelocalization error at the intermolecular region due to an embedding potential applied. This methodology seems especially attractive due to the possibility to consider much larger molecular systems than generally accessible with KS-DFT. However, its use leads to an opposite problem of overly localized spin densities. This drawback was recently lifted with FDE-diab , which extended and generalized the previously known Electron-Transfer Frozen-Density Embedding method (FDE-ET) . The underlying idea of FDE-diab lies in the construction of charge-and spin-localized quasi-diabatic states and computing electronic couplings between them. A similar strategy was successfully applied in various electron-transfer calculations earlier and proved to be very effective. The FDE-diab methodology was validated for a number of dimeric complexes featuring different degrees of the spin-density localization and was shown to be a more reliable and robust approach for spin-density calculations than standard KS-DFT . In this work, we present FDE-diab calculations of spin densities and electronic couplings for RC models of PSI, PSII, and bacteria from Synechococcus elongatus, Thermococcus vulcanus, and Rhodobacter sphaeroides, respectively. We aim at reliable assessments of the spin-density asymmetry in inner pair radical cations and validation of previously proposed photosynthetic models. To that end, we consider a number of molecular systems ranging from dimeric complexes in vacuum to large protein and investigate roles of relative co-factor arrangements.