Summarizing the results presented in this work, we conclude that the FDE-diab methodology is a valuable and robust tool for spin-density calculations of large molecular systems. Avoiding the consequences of the DFT overdelocalization error in the intermolecular regime, it allowed us to obtain reliable spin-density distributions for a number of RC models and to gain a deep insight into the asymmetry of the corresponding SPs. Moreover, the spin-density distribution was found to be highly sensitive to structural arrangements of co-factors. Spin-density distributions of RC models as calculated in this work were not accessible before with existing computational techniques. Further extensions of the FDE-diab approach will soon allow us to go beyond the simplistic two-state model and