New diagram technique for the Anderson model

The generalized Wick theorem for the Anderson model is formulated and, basing on this theorem, the diagram technique for the temperature Green function and the thermodynamic potential is constructed. The main attention is paid to the region of the strong coupling of an impurity atom with metal. As a result of solving the Dyson equations, the impurity Green function is expressed in terms of the mass operator. The contribution to the mass operator and the corrections to the energies of the localized states are obtained in the second order of the perturbation theory.