Structure–property relationships in TMD materials AB2 (A = Nb, Ta; B = S, Se, Te): assessing exchange–correlation functionals

Two-dimensional (2D) transition metal dichalcogenides (TMDs) possess a wide range of functionalities due to their highly tunable chemical, physical, and electronic properties. In this study, we systematically explore the structural, electronic, and phonon characteristics of six TMD systems using density functional theory (DFT) simulations. Our analysis covers both the semiconducting (2H) and metallic (1T) phases of these TMD systems. Specifically, we investigate group-V TMDs (AB2, where A = Nb, Ta, and B = S, Se, Te), examining their structure–property relationships and electronic behaviors to validate the accuracy of various exchange–correlation (XC) functionals, including van der Waals density functionals (vdW-DFs). Our calculations account for both spin–orbit coupling (SOC) and non-SOC (NSOC) scenarios. The results reveal significant impacts on vdW gaps, lattice parameters, and electronic band structures in both the 2H and 1T phases, highlighting their potential for conventional applications.