Orbital-selective insulator-metal transition in V2O3 under external pressure

We present a detailed account of the physics of vanadium sesquioxide (V2O3), a benchmark system for studying correlation-induced metal-insulator transition(s). Based on a detailed perusal of a wide range of experimental data, we stress the importance of multiorbital Coulomb interactions in concert with first-principles local-density approximation (LDA) band structure for a consistent understanding of the insulator-metal (IM) transition under pressure. Using LDA+DMFT (dynamical mean-field theory), we show how the IM transition is of the orbital selective type, driven by large changes in dynamical spectral weight in response to small changes in trigonal field splitting under pressure. Very good quantitative agreement with (i) the switch of orbital occupation and (ii) S=1 at each V3+ site across the IM transition, and (iii) carrier effective mass in the paramagnetic phase, is obtained. Finally, using the LDA+DMFT solution, we have estimated screening-induced renormalization of the local, multiorbital Coulomb interactions. Computation of the one-particle spectral function using these screened values is shown to be in excellent quantitative agreement with very recent experimental (photoemission and x-ray-absorption spectroscopy) results. These findings provide strong support for an orbital-selective Mott transition in paramagnetic V2O3.