摘要： Electronic coupling between excited states is a vital parameter required in order to describe the ultrafast energy and charge transfer processes that occur in photo-responsive organic materials. In such systems short-range Coulombic, exchange, overlap, and configuration interaction effects must all be accounted for. Although a number of methods are available, the evaluation of the coupling between arbitrary excited states remains challenging. In this contribution, a flexible and scalable method for the calculation of short-range electronic coupling between excited states is developed. Excitation- or charge-localized states are projected onto the adiabatic states of a dimeric molecular system using an efficient wavefunction overlap algorithm. In addition to correctly treating Coulombic, exchange and overlap interactions, the inclusion of multistate interactions is inherent in the procedure. The method is then used to disentangle excitation energy transfer, charge-transfer, and charge recombination processes in donor acceptor systems relevant to organic photovoltaics, with a view towards the development of material design principles. Calculations were performed within single-excitation frameworks, but the scheme has the potential to be extended to multireference/higher-order excitation quantum-chemical methods.