The donor-acceptor data set consists of 22 complexes whose S 0 → S 1 transitions primarily involve excitation from the highest occupied MO (HOMO) of a donor molecule into the lowest unoccupied MO (LUMO) of an acceptor, 135 in a van der Waals complex. Although these are CT states on paper, the quantitative extent of CT in these complexes is not large, 135 due to orbital delocalization, and B3LYP continues to perform well (see Fig. ). It exhibits a MAE of 0. longer-range charge separation. Here, B3LYP significantly underestimates the excitation energies, with a of 1.0 eV, whereas BH&H-LYP moves the average error closer to zero and exhibits a smaller error as compared to B(30)LYP. Larger fractions of exact exchange are not beneficial; functionals B(α)LYP with α = 60-70 overestimate all, or nearly all, of the transition energies. This is consistent with the behavior of CIS. Thus, 50% exact exchange emerges once again as a special value that works well even in comparison to similar mixing coefficients.