Theoretical basis for the correlations in heavy Fermions.

It has been fairly obvious on empirical grounds that the excitations in the mixed-valence and the closely related heavy Fermion problem are those of a Fermi-liquid with very strongly renormalized parameters due to the Kondo effect. This has led to a proliferation of pseudo one-electron theories most of which combine the qualitative aspects of the solution of the Kondo problem with the requirement that the solution for the lattice problem obey Bloch's theorem. This is a useful first stab at the problem.