Local variations of charge radii for nuclei with even Z from 84 to 120

Pronounced changes of nuclear charge radii provide a stringent benchmark on the theoretical models and play a vital role in recognizing various nuclear phenomena.In this work,the systematic evolutions of nuclear charge radii along even Z=84-120 isotopic chains are first investigated by the recently developed new ansatz under the covariant density functional.The calculated results show that the shell closure effects of nuclear charge radii appear remarkably at the neutron numbers N=126 and 184.Interestingly,the arch-like shapes of charge radii between these two strong neutron-closed shells are naturally observed.Across the N=184 shell closure,the abrupt increase in charge radii is still evidently emerged.In addition,the rapid raise of nuclear charge radii from the neutron numbers N=138 to N=144 is disclosed clearly in superheavy regions due to the enhanced shape deformation.