Diagram theory for the periodic Anderson model: stationarity of the thermodynamic potential (Q1956849)

This paper deals with the periodic Anderson model under the basic assumption that the Coulomb repulsion of localized electrons is the main parameter of the theory. The results developed in the present paper are applicable to both normal and superconducting states. Unifying the investigation for the two phases has been possible because of introducing the notion of the quantum charge number and rewriting the interaction Hamiltonian in a new form. The main results in this paper are the following: (i) formulations of the Dyson equation for \(c\) electrons and of a Dyson-type equation for \(f\) electrons and their propagators; (ii) skeleton diagrams for the correlation function and the thermodynamic functional; (iii) the stationarity of the renormalized thermodynamic potential under variation of the mass operator.