Transferable screened range-separated hybrids for layered materials: The cases ofMoS2and h-BN

Abstract

Screened range-separated hybrid (SRSH) functionals are of potential interest as a computationally inexpensive yet accurate alternative approach for studying (opto)electronic properties in the solid state. At present, SRSH functionals are typically tuned to reproduce with high accuracy the properties of either bulk or low-dimensional structures, rendering such functionals not only material specific, but also structure specific. The transferability of tuned SRSH functionals between bulk and low-dimensional phases has not been examined systematically and is desirable for straightforward and consistent modeling of size effects in nanostructures. We present a simple yet effective approach for simultaneous tuning of the fraction of short-range exact exchange and the range-separation parameter, which delivers accurate and transferable SRSH functionals for two-dimensional and bulk phases of two prototypical layered materials, molybdenum disulfide (${\mathrm{MoS}}_{2}$) and hexagonal boron nitride (h-BN). The ground-state SRSH band structures, resulting from minimal fitting of the SRSH to a single quasiparticle energy, are found to be in excellent agreement with GW calculations over the entire Brillouin zone. Excited-state properties are predicted using time-dependent density functional theory calculations, based on the SRSH (TD-SRSH) functional. Calculated absorption spectra are found to be in excellent agreement with GW and Bethe-Salpeter equation (BSE) calculations for ${\mathrm{MoS}}_{2}$, but less so for h-BN; the failure of the TD-SRSH for the latter material is examined and a BSE approach based on the SRSH ground state is shown to restore accuracy.