Effect of the Coulomb Interaction on Nuclear Deformation and Drip Lines

Nuclei are self-bound systems in which the strong interaction (nuclear force) plays a dominant role, and the isospin is approximately a good quantum number. The isospin symmetry is primarily violated by electromagnetic interactions, namely Coulomb interactions among protons, the effects of which need be studied to understand the importance of the isospin symmetry. We investigate the effect of the Coulomb interaction on nuclear properties, especially quadrupole deformation and neutron drip line, utilizing the density functional method, which provides a universal description of nuclear systems in the entire nuclear chart. We carry out calculations of even–even nuclei with a proton number of 2≤Z≤60. The results show that the Coulomb interaction plays a significant role in enhancing quadrupole deformation across a wide range of nuclei. We also find that, after including the Coulomb interaction, some nuclei near the neutron drip line become stable against two-neutron emissions, resulting in a shift in the drip line towards larger neutron numbers.