Mott-Hubbard Metal-Insulator Transition in Paramagnetic V_2O_3: a LDA+DMFT(QMC) Study

The electronic properties of paramagnetic V_2O_3 are investigated by the ab-initio computational scheme LDA+DMFT(QMC). This approach merges the local density approximation (LDA) with dynamical mean-field theory (DMFT) and uses numerically exact quantum Monte Carlo simulations (QMC) to solve the effective Anderson impurity model of DMFT. Starting with the crystal structure of metallic V_2O_3 and insulating (V_{0.962}Cr_{0.038})2O_3 we find a Mott-Hubbard metal-insulator-like transition at a Coulomb interaction U\approx 5eV. The calculated spectrum is in very good agreement with experiment. Furthermore, the occupation of the (a{1g},e_{g1}^{\pi},e_{g2}^{\pi}) orbitals and the spin state S=1 determined by us agree with recent polarization dependent X-ray-absorption experiments.