N = 28 isotones: shape coexistence towards proton deficient side

摘要

We have employed the RMF+BCS (relativistic mean-field plus BCS) approach to study the phenomenon of shape coexistence in N = 28 isotones towards the proton-deficient side. Our present investigations include single particle energies, deformations, binding energies as well as excitation energies. It is found that towards the proton-deficient side, N = 28 shell closure disappears due to reduced gap between neutron 1f7/2 and 1f5/2 and the nuclei 40Mg, 42Si, and 44S are found to possess shape coexistence, giving further support to weakening of the shell gap. These results are found to be in excellent agreement with other theoretical and experimental studies and are fortified with a variety of calculations and parameters.