Phase Transitions in Relativistic Models:. Revisiting the Nolen-Schiffer Anomaly

We use the non-linear Walecka model in a Thomas-Fermi approximation to investigate the effects of the ρ - ω mixing term in infinite nuclear matter and in finite nuclei. For finite nuclei the contribution of the isospin mixing term is very large as compared with the expected value to solve the Nolen-Schiffer anomaly.