Asymmetric Hubbard model within generating functional approach in dynamical mean field theory

摘要

In the paper a new analytic approach to the solution of the effective single-site problem in the dynamical meanud field theory is developed. The approach is based on the method of the Kadanoff-Baym generating functional inud the form developed by Izyumov et al. It makes it possible to obtain a closed equation in functional derivativesud for the irreducible part of the single-site particle Green’s function; the solution is constructed iteratively. Asud an application of the proposed approach the asymmetric Hubbard model (AHM) is considered. The inverseud irreducible part Ξ⁻¹σ of the single-site Green’s function is constructed in the linear approximation with respectud to the coherent potential Jσ. Basing on the obtained result, the Green’s function of itinerant particles in theud Falicov-Kimball limit of AHM is considered, and the decoupling schemes in the equations of motion approachud (GH3 approximation, decoupling by Jeschke and Kotliar) are analysed.