Reliable Prediction of Charge Transfer Excitations in Molecular Complexes

We show how charge transfer excitations at molecular complexes can be calculated quantitatively using time-dependent density functional theory (DFT). Predictive power is obtained from range -separated hybrid functionals using non-empirical tuning of the range-splitting parameter. Excellent performance of this approach is obtained for a series of complexes composed of various aromatic donors and the tetracyanoethylene (TCNE) acceptor, paving the way to systematic non-empirical quantitative studies of charge-transfer excitations in real systems.