Many-cloud phonon propogators in the case of acoustical phonons

Abstract

In the High Temperature Superconductors we consider the system of correlated electrons which interect with phonons. In the theory of such sistems an effective way to describe correlation effects of electrons is based on the use of Green’s functions metod. A new diagram technique for the Green’s functions of the strong correlated electrons was proposed by V. A. Moskalenko et al. in. This technique involves simpler creation and annihilation operators for electrons at all intermediate stages of the theory and Hubbard operators only when evaluating final expressions. In the case when the electrons interect whith the acoustical phonons the new elements of the diagram technique appear. The aim of the present paper is to propose the mode how to calculate the such new elements of the diagram technique as the phonon-cloud propagators.