A SIMPLE-MODEL FOR THE 2-SITE ANDERSON HAMILTONIAN

We consider a two-site Anderson Hamiltonian which includes hybridizati on both inside the same and between different sites, as well as Coulom b and exchange interactions between them. An exact diagonalization of this Hamiltonian is performed and the competition between the Kondo an d RKKY interactions is studied as a function of the exchange, J, and t he hybridization parameters. The local, uniform and staggered magnetic susceptibilities are calculated. From the correlation functions it is possible to see that the existence of the Kondo effect depends strong ly on the ratio between the on-site and inter-site hybridizations. No divergence of the susceptibility was found at the critical J value for finite temperatures.