Influence of saturation properties on shell-model calculations

It is shown that the nuclear Hamiltonian scrH separates rigorously into a monopole field ${\mathit{scrH}}_{\mathit{m}}$ and a multipole part ${\mathit{scrH}}_{\mathit{m}}$. ${\mathit{scrH}}_{\mathit{m}}$ is entirely responsible for saturation properties and can be treated phenomenologically with few parameters. When realistic interactions are used for ${\mathit{scrH}}_{\mathit{M}}$ in regions from the p shell to the N=82 isotones, shell-model calculations yield excellent spectroscopy and demand nuclear radii very close to the observed ones.