Hybrid density functional theory meets quasiparticle calculations: A consistent electronic structure approach

We propose a scheme to obtain a system-dependent fraction of exact exchange (alpha) within the framework of hybrid density functional theory (DFT) that is consistent with the G(0)W(0) approach, where G(0) is the noninteracting Green function of the system and W-0 the screened Coulomb interaction. We exploit the formally exact condition of exact DFT that the energy of the highest occupied molecular orbital corresponds to the ionization potential of a finite system. We identify the optimal alpha value for which this statement is obeyed as closely as possible and thereby remove the starting point dependence from the G(0)W(0) method. This combined approach is essential for describing electron transfer (as exemplified by the TTF/TCNQ dimer) and yields the vertical ionization potentials of the G2 benchmark set with a mean absolute percentage error of only approximate to 3%.