Structural characterization and functional assessment of exchange–correlation functionals in van der Waals TMDs AB2 (A = Mo, W; B = S, Se, Te)

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDs) show multi-functionality due to their highly adjustable chemical, physical, and electronic properties. Here, structural, electronic, and phonon response are systematically studied for 06 TMD systems via density functional theory (DFT) simulations. A reversible phase transition is revealed between the semiconducting (2H) phase and the metallic (1T) phase in the stable phases of these TMD systems. Precisely, group-VI TMDs (AB₂, A = Mo, W and B = S, Se, Te) are focused on in these present calculations. Their electronic behavior is assessed to check the accuracy of a few available exchange–correlation (XC) functionals, along with van der Waals density functionals (vdW-DFs). Here, both spin–orbit coupling (SOC) effects and no SOC (NSOC) cases are considered during the calculations. Changes observed in the electronic band structure and density of states for the 2H and 1T phases are worth noticing, which highlights their potential capabilities for conventional device functionalities. These observations not only enable the most accurate XC functional to be found, but also shed light on the potential functionalities of these TMD materials.