Quasiparticle and optical properties of hexagonal boron nitride: from monolayer to bulk

Hexagonal boron nitride (h-BN), an emerging building block for van der Waals heterostructures, has become a research focus in recent years. Interesting, some of the most fundamental aspects of this material are still not fully understood. For example, there are still debates on whether the fundamental band gap is direct or indirect, for both monolayer and bulk h-BN. To the best of our knowledge, the quasiparticle band gap of few-layer h-BN has not been accurately determined. In this talk, we will present fully converged GW+BSE results for monolayer, bilayer and bulk h-BN, aiming to resolve some of the controversies and illustrate the effects of dielectric screening and interlayer interaction on the quasiparticle and optical properties of this material.