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 (α) within the framework of hybrid density functional theory (DFT) that is consistent with the G₀W₀ approach, where G₀ is the noninteracting Green function of the system and W₀ 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 α value for which this statement is obeyed as closely as possible and thereby remove the starting point dependence from the G₀W₀ 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 ≈3%.