Evolution of N=20, 28, 50 shell closures in the 20 Z 30 region in deformed relativistic Hartree-Bogoliubov theory in continuum

Magicity, or shell closure, plays an important role in our understanding of complex nuclear phenomena. In this work, we employ one of the state-of-the-art density functional theories, the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the density functional PC-PK1, to investigate the evolution of the N = 20,28,50 shell closures in the 20 <= Z <= 30 region. We show how these three conventional shell closures evolve from the proton drip line to the neutron drip line by studying the charge radii, two-neutron separation energies, two-neutron gaps, quadrupole deformations, and single-particle levels. In particular, we find that in the 21 <= Z <= 27 region, the N = 50 shell closure disappears or becomes quenched, mainly due to the deformation effects. Similarly, both experimental data and theoretical predictions indicate that the N = 28shell closure disappears in the Mn isotopic chain, mainly due to the deformation effects. The DRHBc theory predicts the existence of the N = 20 shell closure in the Ca, Sc, and Ti isotopic chains, but the existing data for the Ti isotopes suggest the contrary, and therefore further research is needed.