This study aims to fill this gap by performing a comprehensive assessment of different XC functionals for the accurate description of vdW interactions in AB 2 TMD materials (A = Nb, Ta; B = S, Se, Te). The evaluation will consider both spin-orbit coupling (SOC) and non-SOC cases to assess the influence of relativistic effects on the predicted properties . By understanding the strengths and limitations of various XC functionals in capturing the vdW interactions in TMD materials, this research will provide valuable insights for designing and predicting the properties of TMD-based devices. Additionally, it will contribute to the development of system was considered to exhibit semiconductor behavior in the 2H phase, while it was expected to be metallic in the 1T phase. To obtain optimized geometry structures and electronic states, the most accurate and effective functionals were selected for the isolated system. The plane-wave cut-off energy was set to 480 eV, ensuring convergence in the calculations. Moreover, a vacuum space larger than 12 was employed to eliminate any spurious interactions between adjacent slabs.