Quasiparticle Effects in the Bulk and Surface-State Bands of Bi2Se3 and Bi2Te3 Topological Insulators

We investigate the bulk band structures and the surface states of Bi2Se3 and Bi2Te3 topological insulators using first-principles many-body perturbation theory based on the GW approximation. The quasiparticle self-energy corrections introduce significant changes to the bulk band structures, while their effect on the band gaps is opposite in the band-inversion regime compared to the usual situation without band inversion. Parametrized "scissors operators" derived from the bulk studies are then used to investigate the electronic structure of slab models which exhibit topologically protected surface states. The results including self-energy corrections reveal significant shifts of the Dirac points relative to the bulk bands and large gap openings resulting from the interactions between the surface states across the thin slab, both in agreement with experimental data.