Alongside dispersion, many conventional TD-DFT methods lack robustness in treating different types of excitations. Particularly notable challenges arise for long-range excitations (e.g. charge transfer (CT) and Rydberg excitations), low-lying π → π * excitations in polycyclic aromatic hydrocarbons (PAHs) , exciton coupling, , singlet-triplet excitations/gaps , and open-shell excitations. Like for dispersion corrections, dedicated method development efforts have seen improvement for some of these challenging problems. Range separation (RS), as an example, successfully corrects for the wrong asymptotic behaviour of the electron density associated with DFT exchange (in GGAs and hybrids), thus reducing errors for long-range excitations such as CT and Rydberg transitions.