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Charge transfer excitations can be described within TD-DFT, not only by meansof long-range corrected exchange functionals but also with a combination ofwave function theory and TD-DFT based on range separation. The latter approachenables a rigorous formulation of multi-determinantal TD-DFT schemes whereexcitation classes, which are absent in conventional TD-DFT spectra (like forexample double excitations), can be addressed. This paper investigates thecombination of both the long-range MCSCF and SOPPA ans\"atze with a short-rangeDFT (srDFT) description. We find that the combinations of SOPPA or MCSCF withTD-DFT yield better results than could be expected from the pure wave functionschemes. For the Time-Dependent MCSCF short-range DFT ansatz (TD-MC-srDFT)excitation energies calculated over a larger benchmark set of molecules withpredominantly single reference character yield good agreement with theirreference values, and are in general comparable to the long-range correctedfunctional CAM-B3LYP. The SOPPA-srDFT scheme is tested for a subset ofmolecules used for benchmarking TD-MC-srDFT and performs slightly betteragainst the reference data for this small subset. Beyond the proof-of-principlecalculations comprising the first part of this contribution, we additionallystudied the low-lying singlet excited states (S1 and S2) of the retinalchromophore. The chromophore displays multireference character in the groundstate and both excited states exhibit considerable double excitation character,which in turn cannot be described within standard TD-DFT, due to the adiabaticapproximation. However, a TD-MC-srDFT approach can account for themultireference character, and excitation energies are obtained with accuracycomparable to CASPT2, although using a much smaller active space.

Assessment of Charge-Transfer Excitations in Organic Dyes obtained from TD-srDFT Based on Long-Range MP2 and MCSCF Wave Functions