Schedule Nov 06, 2009
A Strong Correlation Study: The Paradigmatic Case of V2O3
Federico Iori (Ecole Polytechnique)

Aim of our work is to study through an ab initio theoretical approach the paramagnetic insulting phase of V2O3 compound, in order to understand better the metal-insulator phase transition subdues by V2O3. It has been shown that at DFT level it’s not possible to describe properly the insulating paramagnetic phase because of a poor treatment of the strong electronic correlation for such systems with d- or f- incomplete shell. Moreover the comparison of DFT density of state with the experimental one is not possible until including many body effect such the ones arising from a direct photoemission spectroscopy. Within a traditional ab initio density functional scheme, the Kohn-Sham eigenvalues can’ t be used for an appropriate description of the electronic bands structures, leading in particular for such a system (VO2, V2O3) to an underestimation or even to a closure of the photoemission band gaps. Moreover, from the experimental point of view, it has been shown that adding small amount of Cr into the V2O3 a sharp metal-insulator transition arises as a function of both Cr concentration and pression at room temperature. We decide to perform ab initio calculation by considering Cr-doped V2O3 supercell system in order to point out which role the presence of the dopant plays on the electronic structure during the metal-insulator paramagnetic transition of the V2O3. Moreover, both the insulating and the metallic phase have been investigated by inelastic xray scattering and compared to the experimental outcomes.

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