PBEsol/HSE functional: a promising candidate for vanadium dioxide (B) characterization

Abstract

A VO₂(B) polymorph has been thoroughly investigated by means of density functional theory (DFT) calculations to evaluate the structure, Raman spectrum, cohesive energy, phonon band structure, an delectronic and optical properties. Among the computed Raman modes, eight of them have been assigned to the VO₂(B) structure in full agreement with the corresponding experimental spectra. The minimized structure of the VO₂(B) polymorph indicated the presence of negative frequencies in its phonon dispersion curves, confirming the dynamic instability of this material. Herein, the combination of generalized gradient approximation (GGA)/PBEsol with a hybrid HSE functional has been employed to perform ab initio calculations on VO₂(B), since the conventional semi-local DFT calculations are believed to underestimate the band gap of materials. By considering the electronic structure calculations, for the first time, we found that the calibration of the PBEsol functional can efficiently model the metallic-like properties of VO₂(B) with a band gap of 0.26 eV, while the corresponding electronic bandgap of VO₂(B) based on the HSE functional possesses a larger band gap of 0.67 eV. The prediction of optical characteristics of VO₂(B) indicated that the optical conductivity of VO₂(B) lies in the infrared region of light. This work strongly suggests the combination of GGA/PBEsol with HSE hybrid functionals to carefully describe the physical properties of smart materials exploitable in electronics and optoelectronics applications. The nanostructure of VO₂(B) looks promising for IR photodetectors and smart windows applications as a semiconductor material with excellent optical features. It is predicted that in the future VO₂(B) will continue to expand the envelope of its capabilities because of its remarkable properties.