The study focuses on investigating the properties of AB2 transition metal dichalcogenides (TMDCs), where A represents Mo and W, and B represents S, Se, and Te. Therefore, a total of 06 unique combinations of A and B elements are considered. Each combination exhibits two distinct phases, namely the 1T and 2H phases, resulting in a total of 12 systems under investigation. The objective of this research is to conduct a comprehensive analysis of these systems, including geometry optimization, total energy calculations, electronic band structure analysis, Fermi surface characterization, and phonon calculations . Both spin-orbit coupling (SOC) and non-SOC (NSOC) cases are considered in these calculations. To ensure accurate results for the aforementioned calculations, four different exchange-correlation functionals are employed, namely LDA, PBE, PBESol, and SCAN. These functionals are chosen for their ability to provide reliable ab initio calculations. Additionally, five different van der Waals (vdW) corrections are applied to the systems, including optB88-vdW, optPBE-vdW, vdW-DF2, rev-vdW-DF2, and SCAN+rVV10. By incorporating these vdW corrections, the impact of weak interlayer interactions on the properties of the TMDC systems can be accurately captured. Considering both the 1T and 2H phases for each of the 06 TMDC systems, a total of 12 sets of calculations are performed. Consequently, each TMDC system requires 18 sets of calculations to comprehensively analyze both phases. The detailed geometry structure of the systems is provided below, serving as a valuable reference for the subsequent analyses and discussions in this study. All the geometry optimization calculations and energy calculations have been performed and completed for all the systems in NSOC case and the results are shown below in tabular form.