Electronic Structure–Kinetics Correlation in Polymorphic Phase Transitions

Understanding the kinetics of polymorphic transitions—transformations between different crystal structures of the same compound—remains a major challenge due to their complex atomic-scale mechanisms and intertwined thermodynamic and electronic factors. In particular, how the transition kinetics correlate with the electronic structures of different polymorphs is still poorly understood. We systematically investigate a series of materials undergoing similar polymorphic transitions, focusing on the 2H → 1T phase change in two-dimensional transition metal dichalcogenides (TMDs), including MoX₂ and WX₂ (X = S, Se, Te). Using the generalized solid-state nudged elastic band (G-SSNEB) method, we find that the saddle-point structure exhibits feature intermediate between the two parent polymorphs. Bond-specific electronic structure analyses via crystal orbital Hamiltonian population (COHP) reveal that as the 2H phase transforms to 1T, the antibonding states shift toward the Fermi level, peaking at the transition state. Extending this analysis to wurtzite-to-cubic (AlN, GaN, ZnO) and monoclinic-to-tetragonal (HfO₂, VO₂, ZrO₂) transformations, we show that bond-specific electronic characteristics fundamentally govern the activation barriers and kinetic pathways of polymorphic transitions.