MOTT-HUBBARD TRANSITION AND ANDERSON LOCALIZATION: A GENERALIZED DYNAMICAL MEAN-FIELD THEORY APPROACH
Kuchinskii E.Z., Nekrasov I.A., Sadovskii M.V.

Received: October 4, 2007

PACS: 71.10.Fd, 71.27.+a, 71.30.+h

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The density of states, the dynamic (optical) conductivity, and the phase diagram of a strongly correlated and strongly disordered paramagnetic Anderson-Hubbard model are analyzed within the generalized dynamical mean-field theory (DMFT+Σ approximation). Strong correlations are taken into account by the DMFT, and disorder is taken into account via an appropriate generalization of the self-consistent theory of localization. The DMFT effective single-impurity problem is solved by the numerical renormalization group (NRG); we consider the three-dimensional system with a semi-elliptic density of states. The correlated metal, Mott insulator, and correlated Anderson insulator phases are identified via the evolution of the density of states and dynamic conductivity, demonstrating both the Mott-Hubbard and Anderson metal-insulator transition and allowing the construction of the complete zero-temperature phase diagram of the Anderson-Hubbard model. Rather unusual is the possibility of a disorder-induced Mott insulator-to-metal transition.