Octupole Deformations of Even-Even Rn, Th, and U Nuclei in Relativistic Mean Field Theory

The octupole deformations and other ground state properties of even-even Rn, Th and U isotopes are investigated systematically within the framework of the reflection asymmetric relativistic mean field (RAS-RMF) model. The calculation results reproduce the binding energies and the quadrupole deformations well. The calculation results indicate these nuclei at ground states evolve from nearly-spherical (N = 130) shape to quadrupole deformation shape with the increase of the neutron number. It is also found that among the Rn isotopes, only (222,224)Rn are octupole deformed and the octupole deformations for them are small. However, more nuclei (N similar or equal to 134-148) in Th and U isotopes are octupole deformed and the octupole deformations for some of them are significant (vertical bar beta vertical bar similar to 0.1 or even larger).