Computational 2D Materials Database: Electronic Structure of Transition-Metal Dichalcogenides and Oxides

TLDR

The study presents a comprehensive first‑principles analysis of 51 semiconducting monolayer transition‑metal dichalcogenides and oxides, focusing on trends and correlations in their electronic structure rather than detailed material‑specific analysis. The authors compute quasiparticle band structures with spin–orbit coupling using the G0W0 approximation, compare them to various DFT descriptions, evaluate band‑edge positions for band alignment, analyze lattice‑constant sensitivity, and extract dielectric functions and effective masses to estimate exciton binding energies with a 2D hydrogenic model. The work identifies convergence pitfalls in GW calculations for 2D materials, offers solutions, analyzes lattice‑constant sensitivity, provides exciton binding‑energy estimates, and makes all computed data available in an open database.

Abstract

We present a comprehensive first-principles study of the electronic structure of 51 semiconducting monolayer transition-metal dichalcogenides and -oxides in the 2H and 1T hexagonal phases. The quasiparticle (QP) band structures with spin-orbit coupling are calculated in the G(0)W(0) approximation, and comparison is made with different density functional theory descriptions. Pitfalls related to the convergence of GW calculations for two-dimensional (2D) materials are discussed together with possible solutions. The monolayer band edge positions relative to vacuum are used to estimate the band alignment at various heterostructure interfaces. The sensitivity of the band structures to the in-plane lattice constant is analyzed and rationalized in terms of the electronic structure. Finally, the q-dependent dielectric functions and effective electron and hole masses are obtained from the QP band structure and used as input to a 2D hydrogenic model to estimate exciton binding energies. Throughout the paper we focus on trends and correlations in the electronic structure rather than detailed analysis of specific materials. All the computed data is available in an open database.