Prediction of Potential Charge Density Wave in Monolayer H‐NbS ₂ by First‐Principles Calculations

We systematically investigate the potential charge density wave (CDW) phases in monolayer H‐phase NbS 2 via first‐principles calculations based on density functional theory. Our results reveal a distinct phonon soft mode at the high‐symmetry M point in the phonon spectrum of the fullyrelaxed monolayer H‐NbS 2 primitive cell under a Gaussian broadening parameter of 0.1 eV. We further expanded 2 × 2 superstructure to a 6 × 6 supercell due to Brillouin zone folding and obtained a thermodynamically stable superstructure with no imaginary frequency. The minimum periodic unit of this stabilized superstructure manifests as a 1 × 3 CDW phase, characterized by significant symmetry breaking and lattice reconstruction of Nb atoms. This study identifies a latent 1 × 3 CDW phase in monolayer H‐NbS 2 , demonstrating that our approach can effectively reveal novel CDW phases in conventional phase transitions and providing theoretical support for experimental exploration of potential CDW phases.