Green's function solution of the Kondo problem and universality of the thermodynamic properties (invited)

Using a functional derivative approach, we derive, for the nondegenerateAnderson model of dilute magnetic alloys, a Green's function, which is valid atall temperatures and which accurately exhibits the Kondo effect. This is madepossible by explicitly satisfying the Baym criterion for the macroscopicconservation of particle-number, momentum and energy: a criterion not satisfied by any of the earlier Green's function treatments of the Kondo model or the Anderson model. The free energy of the system is calculated and the universality of all the thermodynamic properties including resistivity is analytically demonstrated. The temperature-dependent susceptibility chi(T) and specific heat C(T) thus calculated are found to be almost indistinguishable from the results of the renormalization group theory