Extracting the hybrid functional mixing parameter from a GW quasiparticle approach

Abstract Relying on quasiparticle GW electronic structure calculations we present an approach to obtain an “optimal value” of the so called “mixing parameter,” α , in hybrid functional calculations. We show that when this “optimal” amount of exact exchange (we denote this as α opt ) is mixed with the semi‐local PBE exchange‐correlation functional, the net quasiparticle corrections to the PBE Kohn–Sham eigenvalues attain a minimum value. We employ this approach to perovskite oxide insulators SrTiO 3 and PbTiO 3 and compare that to the widely studied semiconductor compounds, Si and Ge. A system dependence of the optimal choice of the mixing parameter is revealed.