New diagram technique for the Anderson model

A generalized Wick theorem for the Anderson model is formulated. On this basis, the diagram technique for the temperature Green's function and the thermodynamic potential is developed. Particular attention is paid to the region of strong coupling of an impurity atom with a metal. The Dyson equations are solved and the impurity Green's function is expressed in terms of the mass operator. The contribution to the mass operator and corrections to the energies of localized states are obtained in the second order of perturbation theory.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 109, No. 2, pp. 279–294, November, 1996.