Hybridization in correlated bands studied with the Gutzwiller method: Application to fluctuating valence and heavy fermions

A model with two hybridized orbitals per site, one of which is correlated and the other is not, is considered. A variational wave function of the Gutzwiller form is used to calculate the mass enhancement. Unlike models with one orbital per site, there is no metal-insulator transition in the model because the occupation in the correlated orbital deviates from unity as the correlation energy increases. The binding energy and the effective mass as a function of the correlation energy and the hybridization energy is calculated. The relationship of the wave function used to wave functions explicitly showing the Kondo effect is discussed.