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SKM-SYOP: SKM-Symposium Elementary Processes in Organic Photovoltaics

SKM-SYOP 1: Elementary Processes in Organic Photovoltaics

SKM-SYOP 1.3: Hauptvortrag

Montag, 14. März 2011, 11:30–12:00, TRE Ma

Reliable prediction of charge transfer excitations using optimally tuned range-separated hybrid functionals — •Leeor Kronik — Weizmann Institute of Science, Rehovoth, Israel

Charge transfer excitations are an essential concept in organic photovoltaics. Typically, electron excitations are well-described from first principles using time-dependent density functional theory (DFT). However, this is not the case for charge transfer excitations, which are very poorly described by all widely used approximations within time-dependent DFT.

Here, we overcome this difficulty by presenting a broadly-applicable, non-empirical first-principles approach based on using a range-separated hybrid functional within the generalized Kohn-Sham approach to time-dependent DFT. Its key element is the optimal choice of a range-separation parameter such that Koopmans' theorem is obeyed as closely as possible. We explain the physics behind this approach and demonstrate its validity, accuracy, and advantages for determining charge transfer excitation energies. Additionally, we show that the same approach can be used for predicting fundamental gaps of finite objects directly from generalized Kohn-Sham DFT eigenvalues.

* Work performed in collaboration with T. Stein and R. Baer, Hebrew University, Jerusalem