Nuclear surface energy and neutron-star matter

Direct calculations of the nuclear surface energy are made for a Hamiltonian containing the Skyrme nucleon-nucleon interaction. A plane surface separating nuclear matter and a neutron gas or a vacuum is considered in Hartree-Fock and Thomas-Fermi approximations. These surface energies are incorporated in the compressible liquid-drop model to obtain properties of neutron-star matter. The Hartree-Fock results lead to Z values for the nuclei roughly constant at around Z∼36-38.