Superdeformation in the newly discovered superheavy elements

The structures of newly discovered superheavy elements with the proton numb er Z = 110-112, 114, 116, 118 and of their alpha -decay chain nuclei are in vestigated using the self-consistent relativistic mean-field (RMF) theory. Extensive calculations show that the experimental data on the cy-decay ener gies are well reproduced by the RMF theory. We find sometimes shape coexist ence in superheavy nuclei and a superdeformed prolate configuration becomes the ground state of the new superheavy elements. The superdeformation coul d lead to a slightly deeper binding and give a longer lifetime for superhea vy nuclei than expected. This may he a new mechanism for the appearance of the superheavy island, A systematic comparison with other models for the ca lculated binding energies and deformations is carried out, and predictions on the properties of unknown neighbouring superheavy nuclei are made for fu rther comparison with future experiments. (C) 2001 Elsevier Science B.V. Al l rights reserved.