Title: APPROXIMATE ANALYTICAL DYNAMICAL MEAN-FIELD APPROACH TO STRONGLY CORRELATED ELECTRON SYSTEMS
Author(s): I.V.Stasyuk (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79011 Lviv, Ukraine)

An approximate analytical scheme of the dynamical mean-field theory (DMFT), that is used for electron systems with Hubbard correlations and is exact in the limit of the infinite dimensionality of a space, is developed. The effective single-site problem arising in the framework of this method is formulated in terms of the auxiliary Fermi-field. The irreducible Green's function technique with the projecting on the Hubbard basis of Fermi-operators is used for its solution. A system of DMFT equations is obtained in the approximation which is a generalization of the Hubbard-III approximation and combines it with a self-consistent renormalization of the local electron levels. It is shown that the proposed approach includes as simple specific cases a number of known approximations (Hubbard-III, AA, MAA, \dots) based on the assumption of the single-site structure of the electron self-energy.

Comments: Figs. 0, Refs. 27, Tabs. 0.