Reliable electronic and optical characterization of 2D materials using density functional theory

In recent years, there has been a widespread and intense interest in the determination of electronic structure and optical properties of two-dimensional van der Waals (vdW) materials because of their inmense tunnability of their electronic and optical properties. This is due to their potential impact in a vast number of scientific fields and technologies, ranging from nanoelectronics to photovoltaic or photocatalytic applications. Accurately predicting these properties from first principles is an outstanding challenge. In this talk I will show this challenge can be overcome using density functional theory (DFT). I will present how to accurately determine the electronic structure and excitonic properties, specifically the optical absorption spectra of low-dimensional vdW materials with DFT and a new flavor of screened range-separated hybrid functionals [1, 2] based on the use of localized Wannier functions. The parameters defining these functionals are material- and structure-dependent. I will show a non-empirical process of determining the functional parameters and I will apply it to prototypical vdW materials. The obtained electronic and optical properties display a level of accuracy comparable to that of ab initio many-body perturbation techniques, such as GW and the Bethe-Salpeter quation.   [1] M. Camarasa-Gómez, A. Ramasubramaniam, J. B. Neaton, L. Kronik, Phys. Rev. Materials 7, 104001 (2023) [2] M. Camarasa-Gómez, Stephen E. Gant, G. Ohad, J. B. Neaton, A. Ramasubramaniam, L. Kronik (arXiv:2405.00643)