The thermodynamics of the Kondo model are formulated in terms of coupled integral equations and various properties, in particular the scaling property, are deduced. Then, with definition of the various scales parametrizing various asymptotic regions of the $H-T$ plane, universal numbers are calculated and, in particular, Wilson's result is obtained analytically.

• Received 29 September 1980

DOI:https://doi.org/10.1103/PhysRevLett.46.356