When the Skyrme equations of state (EOS) are constrained by the binding energies and rms charge radii of doubly-magic nuclei, the value of the neutron EOS is fixed at a density of 0.10 neutrons/fm^3. If one adds information on the neutron skins then the derivative at this point can be determined. The value and derivative can be used to obtain the entire Skyrme EOS. EOS results for neutrons, symmetric nuclear matter, and the symmetry energy will be shown.
The neutron EOS can also be constrained to reproduce ab-initio calculations for low-density neutron matter in addition to the binding energies and charge radii of doubly-magic nuclei. This determines the Skyrme neutron EOS and its related properties within a rather narrow error band. The neutron skin of 208Pb is predicted to be R(np) = 0.182(12) fm.