Electronic and Optical Properties of Monoclinic and Rhombohedral Vanadium Sesquioxide

T The electronic and optical properties of monoclinic and rhombohedral V<,2>O<,3> are investigated in the framework of density functional theory(DFT)and GGA+U. It is found that, the metal-insulator transition(MIT)in V<,2>O<,3> is induced by the on-site correlation effect, accompanied with a distinct orbital occupation change. The MIT is independent of the structural transition. The theoretical energy gap 0.6 eV agrees with the experimental value of 0.664±0.05 eV very well.Subsequently, the optical properties are also investigated. Interestingly, the insulating V<,2>O<,3> shows minimal absorption in the infrared region, but the metallic V<,2>O<,3> becomes opaque in such region.Therefore, a threshold at about 1 eV interprets the experimental charge gap(Perucchi et al., 2009)theoretically. Such infrared thermochromism makes it a potential candidate for several optical applications.