From Insulator to Metal: Theoretical Assessment on the Optical Properties of Vanadium Dioxide Using Many-Body First-Principles Approaches

Vanadium dioxide (VO₂) exhibits a temperature-driven insulator-to-metal transition, making it a promising material for optical and electronic applications. In this study, we perform a systematic first-principles investigation of the electronic and optical properties of VO₂ in its monoclinic (M₁) and rutile (R) phases using density functional theory (DFT), many-body perturbation theory (G₀W₀), and the Bethe-Salpeter equation (BSE). Our results reveal that excitonic effects play a crucial role in accurately describing the dielectric response of the semiconducting M₁ phase, with G₀W₀/BSE and PBE/BSE approaches yielding optical spectra in excellent agreement with experimental data. For the metallic R phase, we find that the random phase approximation (RPA) at the PBE level provides a reliable description of its optical properties, particularly in the visible range, as long as intraband contributions are included. The frequency-dependent dielectric functions presented in this work achieve the required accuracy for large-scale optical simulations relevant to smart coatings and tunable infrared devices. To support further research and applications, we provide our computed optical data in an open-access repository on ZENODO.