Historically, a point of some debate was the fact that the PBE and B3LYP functionals both predict reasonably accurate excitation energies for both the 1 L a and 1 L b states, with comparable errors in each, for DMABN and other small donor-π-acceptor molecules. A resolution to this apparent paradox comes in the form of metric for quantifying CT character, that will be introduced below but which ultimately suggests that the extent of CT in the planar geometry of DMABN is not very large. Only in hindsight can this be inferred from the densities in Fig. , which do not suggest any dramatic difference between S 1 and S 2 at the ground-state geometry. (The difference is much more pronounced at the twisted geometry.) As such, DMABN serves as a cautionary tale to indicate that one must be careful with blanket statements that TD-DFT fails categorically for CT excitations, or at least one must be careful about what gets called a CT excitation. Energies for truly long-range CT excitations will indeed be systematically (and catastrophically) underestimated using GGA functionals, but errors may be small if the donor and acceptor orbitals are not completely separated in space. In the planar geometry of ground-state DMABN, these orbitals are clearly not well-separated in space. Opaque and wire mesh surfaces encapsulate 50% and 90% of each density, respectively. TD-DFT/TDA calculations were performed using LRC-ωPBE/6-31G* with a dielectric constant of 37.5 (representing acetonitrile).