Optical properties of bulk semiconductors and graphene/boron nitride: The Bethe-Salpeter equation with derivative discontinuity-corrected density functional energies

Abstract

We present an efficient implementation of the Bethe-Salpeter equation (BSE) for optical properties of materials in the projector augmented wave method GPAW. Single-particle energies and wave functions are obtained from the GLLBSC functional which explicitly includes the derivative discontinuity, is computationally inexpensive, and yields excellent fundamental gaps. Electron-hole interactions are included through the BSE using the statically screened interaction evaluated in the random phase approximation. For a representative set of semiconductors and insulators we find excellent agreement with experiments for the dielectric functions, onset of absorption, and lowest excitonic features. For the two-dimensional systems of graphene and hexagonal boron-nitride (h-BN) we find good agreement with previous many-body calculations. For the graphene/h-BN interface, we find that the fundamental and optical gaps of the h-BN layer are reduced by 2.0 eV and 0.7 eV, respectively, compared to freestanding h-BN. This reduction is due to image charge screening which shows up in the GLLBSC calculation as a reduction (vanishing) of the derivative discontinuity.

Optoelectronic properties of single-layer, double-layer, and bulk tin sulfide: A theoretical study

“…48 This functional accounts explicitly for the discontinuity in the derivative of (semi-)local exchange-correlation functionals such as LDA, and it has been successfully used to predict the band gap of prototypical bulk and low-dimensional semiconductors and insulators. 47,49,50 The discontinuity depends on the space coordinate but a constant value is obtained by first-order perturbation theory. More details on the formalism are given in the work of Kuisma et al 47 For k-space integration, a Monkhorst-Pack mesh of 1 Â 8 Â 8 k-points was used for the single-layer and double-layer structures and a mesh of 4 Â 8 Â 8 k-points was used for the bulk structure.…”

How dielectric screening in two-dimensional crystals affects the convergence of excited-state calculations: Monolayer MoS2

“…Atomically thin two-dimensional (2D) materials such as graphene, hexagonal boron nitride, and transition-metal dichalcogenides (TMDC) possess unique electronic and optical properties including high intrinsic carrier mobilities, [1][2][3] tunable band gaps, 4,5 and strong light-matter interactions. [6][7][8][9] These features, combined with the possibility of engineering their electronic properties further via strain, alloying, or stacking, make the 2D materials ideal as building blocks for new optoelectronic structures and devices with minimal sizes and performances surpassing present technologies.…”

Quasiparticle GW calculations for solids, molecules, and two-dimensional materials

“…[12][13][14]. Beyond the calculation of QP energies, the GW method also serves as starting point for the calculation of optical spectra from the Bethe-Salpeter equation (BSE) [15][16][17][18] and for quantitatively accurate modeling of electron transport at metal-molecule interfaces where the alignment of the molecular energy levels with the metal Fermi level is particularly important. accuracy, while better results were achieved when starting from Hartree-Fock or hybrid calculations.…”