Speaker
Description
Band-gap problem is the fundamental issue which underlies the predictive inaccuracy in a number of applications, e.g., the determination of defect energy levels in solid. In this talk, we will first show that defect energy levels can be obtained reliably through hybrid-functional and many-body $GW$ calculations provided that the band gaps are well accounted for. We will then outline recent developments towards accurate fundamental band gaps in the context of self-consistent $GW$ and dielectric-dependent hybrid functionals, both of which are nonempirical in nature. Specifically, the self-consistent $GW$ with an efficient vertex-corrections scheme gives highly accurate electronic structures. The dielectric-dependent hybrid functional achieves the comparable accuracy for a variety of materials and is computationally more practical for large-scale systems.
