Importance of theV3d–O2phybridization in the Mott-Hubbard materialV2O3

Abstract

We studied the changes in the electronic structure of ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ using a cluster model. The calculations included fluctuations from the coherent band in the metallic phase and nonlocal Mott-Hubbard fluctuations in the insulating phase. The incoherent structure is mostly related to the usual ligand screening channel $(3{d}^{2}\underset{̱}{L})$. The coherent peak in the metallic phase corresponds to coherent band fluctuations $(3{d}^{2}\underset{̱}{C})$. However, The Mott-Hubbard screened state in the insulating phase $(3{d}^{2}\underset{̱}{D})$ appears at higher energies. The transfer of spectral weight from the $3{d}^{2}\underset{̱}{L}$ to the $3{d}^{2}\underset{̱}{D}$ state produces the opening of the band gap. The photon energy dependence of the spectra is partly related to the relative $\mathrm{V}\phantom{\rule{0.2em}{0ex}}3d--\mathrm{O}\phantom{\rule{0.2em}{0ex}}2p$ cross sections. The calculations reproduce also the experimental changes observed in the $\mathrm{V}\phantom{\rule{0.2em}{0ex}}1s$ core-level spectra. The above results suggest that the Mott-Hubbard transition in ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ requires a multiband model.