Evolution of the d∥ band across the metal–insulator transition in VO2

We studied the evolution of the electronic structure of VO2 across the metal–insulator transition. The electronic structure was calculated using the standard TB–LMTO–ASA method. The calculated DOS was compared to previous photoemission and X-ray absorption spectra. The electronic structure is discussed in terms of the usual molecular–orbital scheme. In the metallic phase, the d∥ band appears at the bottom of the V 3d bands and crosses the Fermi level. In the insulating phase, the d∥ band is split around 2 eV opening a pseudo band gap at the Fermi level. The largest effect of the splitting appears in the unoccupied part of the d∥ band. The calculated value of the splitting accounts for 77% of the experimental value, 2.6 eV. The results suggest that electron–lattice interaction seems to be the dominant factor in the splitting of the d∥ band.