This type of analysis can be used to demonstrate how different exchange-correlation functionals may predict qualitatively divergent behavior for excitonic states in multichromophore systems. In such cases, FE states can mix with either localized CT states or delocalized CR states and the extent of mixing is sensitive to the long-range behavior of the functional in question, especially with regard to the fraction (if any) of Hartree-Fock exchange. The energetic position of CT and/or CR states is sensitive to this fraction, to a much greater extent than localized excitations such as ππ * or nπ * , 26 so adjusting the fraction of exact exchange has the effect of tuning charge-separated states in or out of resonance. As an example, Fig. shows heat maps of Ω for the lowest four singlet excited states of a (pentacene) 4 cluster taken from a supercell of the crystalline material, computed using four different density functionals. Significant discrepancies are observed amongst different functionals in these data. Using the ωB97X-V functional, for example, the states S 1 to S 4 are mostly CR states, which is evident from the strong anti-diagonal character of the Ω heat maps; consult Table for a guide. For example, the S 1 and S 4 states primarily involve mixing basis states