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We report the band structures and excitonic properties of delafossites $CuMO_2$ (M = Al, Ga, In, Sc, Y, Cr) calculated using the state-of-the-art $textit{GW}$-BSE approach. We find that all the delafossites are indirect band gap semiconductors with large exciton binding energies, varying from 0.24 to 0.44 eV. The lowest and strongest exciton, mainly contributed from either Cu 3$textit{d}$ $rightarrow$ Cu 3$textit{p}$ (Al, Ga, In) or Cu 3$textit{d}$ $rightarrow$ M 3$textit{d}$ (M = Sc, Y, Cr) transitions, is always located at $L$ point of the rhombohedral Brillouin zone. Taking the electron-hole effect into account, our theoretical band gaps exhibit nice agreement with experiments.
We study the optical properties of the Ruddlesden-Popper series of iridates Sr$_{n+1}$Ir$_n$O$_{3n+1}$ ($n$=1, 2 and $infty$) by solving the Bethe-Salpeter equation (BSE), where the quasiparticle (QP) energies and screened interactions $W$ are obtain
Using the GW approximation, we study the electronic structure of the recently synthesized hydrogenated graphene, named graphane. For both conformations, the minimum band gap is found to be direct at the $Gamma$ point, and it has a value of 5.4 eV in
We report diffusion quantum Monte Carlo (DMC) and many-body $GW$ calculations of the electronic band gaps of monolayer and bulk hexagonal boron nitride (hBN). We find the monolayer band gap to be indirect. $GW$ predicts much smaller quasiparticle gap
The full-potential linearized augmented plane wave method with the generalized gradient approximation for the exchange-correlation potential (FLAPW-GGA) is used to predict the electronic and elastic properties of the newly discovered superconducting
The discovery of atomically thin two-dimensional (2D) magnetic semiconductors has triggered enormous research interest recently. In this work, we use first-principles many-body perturbation theory to study a prototypical 2D ferromagnetic semiconducto