Accurate and approximative many-body methods for optical gap of semiconducting 2D materials*

Many-body GW approximation and Bethe-Salpeter equation (BSE) are considered as state-of-the-art methods for reliable prediction of quasiparticle (QP) and optical gaps of bulk materials, respectively. On the other hand, GW and BSE methods are still computationally challenging and its usage for a larger supercell is almost unfeasible. We show which factors are important to obtain accurate QP and optical gaps by GW+BSE approach and we evaluate the magnitudes of such factors [1-3]. We also show that several computationally cheap approximations based on time-dependent DFT can be used as accurate alternative to GW+BSE approach and promising applications on selected vdW heterostructures are demonstrated [3-4].

[1] F. Karlicky, J. Turon, Carbon 135, 134 (2018).
[2] F. Karlicky, M. Otyepka, Ann. Phys. 526, 408 (2014).
[3] M. Kolos, F. Karlicky, Phys. Chem. Chem. Phys. 21, 3999 (2019).
[4] T. Ketolainen, N. Machacova, F. Karlicky, to be submitted (2019).