State Dependence of Coulomb Interaction in Nuclei

The Coulomb energies of valence particles in ${\mathrm{Ne}}^{18}$ and ${\mathrm{Ti}}^{42}$ are calculated using realistic two-particle wave functions. The extra correlation in the configuration-mixed wave functions increases the Coulomb interaction by ∼150 keV for the $0^{+}$ state, and ∼50 keV for the $2^{+}$. This large effect brings the theoretical binding-energy differences of the mass-18 and mass-42 isospin triplets into agreement with experiment, but yields an average interaction larger than required by the binding-energy systematics of heavier nuclei.