Structural stability and electronic correlations in the Janus-Kagome van der Waals semiconductors M3TeI7(M = Nb, Ta).

The structural and electronic properties of the Janus-Kagome compounds NbTeIand TaTeIare investigated through first-principles density functional theory (DFT) calculations. These layered materials combine the electronic characteristics of Kagome lattices with the intrinsic polarity arising from Janus structural asymmetry, making them promising platforms for exploring flat-band physics in low-dimensional systems. The influence of several van der Waals correction schemes is systematically examined, revealing that the DFT-D3 method with Becke-Johnson damping provides the best agreement with available experimental lattice parameters. Both compounds are found to be dynamically and thermally stable. The electronic structures preserve the characteristic Kagome features, with transition-metalorbitals dominating the states near the flat-band regions. Furthermore, bonding analyses and linear-response calculations of the effective Hubbardparameter provide a consistent description of the bonding and correlation effects in these systems. The results provide a consistent theoretical description of the structural stability and electronic properties of NbTeIand TaTeI, contributing to a deeper understanding of Janus-Kagome semiconductors and offering a reliable framework for future studies of related two-dimensional materials.