Tuning Electronic Band Properties in Binary Chalcogenides with Extrinsic and Intrinsic Strain: A First-Principles Study

We assess the relationship of the electronic band structure and atomic relaxation in Bi₂Se₃ and Bi₂Te₃. We use first-principles Density Functional theory (DFT) method to control for the influence of the exchange-correlation functional (XCF) and slab thickness. After a thorough analysis, in which we modulate the input parameters over a broad swathe of the computational space, we conclude that the GGA+vdW functional reproduces experimental results with best relative computational efficiency. In addition, we conclude that the use of experimental lattice parameters (ELP)—instead of ab initio ones—is sufficient to generate accurate descriptions of the electronic properties. After making this determination, we study the effect of doping on the electronic structure of As₂Te₃ and Bi₂Se₃, in the context of another study on the effect of biaxial strain on the same. In accordance with the first set of results, we use GGA+vdW as the XCF, and we use the ELP as the basis of both materials’ unrelaxed structure. Our results are valuable for the development of mechanisms for tuning the electronic properties of topological and trivial insulators.