  We revisit the Kotliar-Ruckenstein (KR) slave boson saddle point evaluation
for a two-site correlated electron model. As the model can be solved
analytically, it is possible to compare the KR saddle point results to the
exact many particle levels. The considered two site cluster mimics an
infinite-$U$ single-impurity Anderson model with a nearest neighbor Coulomb
interaction: one site is strongly correlated with an infinite local Coulomb
repulsion which hybridizes with the second site, on which the local Coulomb
repulsion vanishes. Making use of the flexibility of the representation we
introduce appropriate weight factors in the KR saddle point scheme. Ground
state and all excitation levels agree with the exact diagonalization results.
Thermodynamics and correlation functions may be recovered in a suitably
renormalized saddle point evaluation.
