The electronic excitation energy transfer (EET) in which the excitation energy is transferred via excitons play an important role in diverse areas of research including biological systems and optoelectronic devices. Intermolecular electronic couplings between two non-covalent molecules are essential for a fully understanding of these processes. On the other hand, the energy evolution is crucial for a more direct picture of EET that also applies to estimate the energy transfer rates, especially in ultrafast process. In this work, we develop a new method for an accurate and numerically efficient calculation of the intermolecular electronic couplings. In this approach, the relative diabatic excited states are constructed by the block-localized Kohn-Sham (BLKS) orbitals which are fully optimized by maximum occupation method (MOM), then the diabatic couplings as well as the adiabatic excited states can be computed directly according to the multi-state density functional theory (MSDFT) framework. Thus, this approach can apply to both strong coupling (Dexter) and weak coupling (Forster) regime. Furthermore, the energy transfer rate can be estimated by the time evolution of two electronic diabatic states according to solving the time-dependent Schrodinger equation based on MSDFT effective Hamiltonian. The method proposed by this work offers a reliable and flexible strategy to deal with EET in molecular systems.

Electronic couplings for the intermolecular energy transfer

2019 Spring National Meeting

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