Microscopic origin of dopant-induced destabilization of the monoclinic insulating phase in vanadium dioxide: a DFT + U study

Vanadium dioxide (VO2) exhibits a metal–insulator transition (MIT) associated with a structural transformation between monoclinic and rutile phases. While chemical doping is widely used to tune the transition temperature, the microscopic mechanisms underlying dopant-induced insulating phase destabilization remain unclear. Here, we present a systematic density functional theory with Hubbard U correction (DFT+U) study of substitutional doping in VO2, covering a broad range of dopant elements at dilute concentrations. By consistently evaluating phase energetics, local structural distortions, elastic strain, and electronic structure, we find that all dopants considered destabilize the insulating monoclinic phase and reduce the transition temperature, in agreement with experimental trends. Our analysis reveals that this behavior arises from a dopant-dependent interplay between frustration of V–V Peierls dimerization, increased elastic mismatch between the competing phases, and electronic reorganization through gap narrowing, band filling, or in-gap state formation. These results provide a unified microscopic framework for understanding dopant-controlled MIT tuning in VO2 and offer guidance for designing materials with tailored transition temperatures.