Octupole deformation in the ground states of even-even nuclei: A global analysis within the covariant density functional theory

A systematic investigation of octupole deformed nuclei is presented for\neven-even systems with $Z\\leq 106$ located between the two-proton and\ntwo-neutron drip lines. For this study we use five most up-to-date covariant\nenergy density functionals of different types, with a non-linear meson\ncoupling, with density dependent meson couplings, and with density-dependent\nzero-range interactions. Pairing correlations are treated within relativistic\nHartree-Bogoliubov (RHB) theory based on an effective separable\nparticle-particle interaction of finite range. This allows us to assess\ntheoretical uncertainties within the present covariant models for the\nprediction of physical observables relevant for octupole deformed nuclei. In\naddition, a detailed comparison with the predictions of non-relativistic models\nis performed. A new region of octupole deformation, centered around $Z\\sim 98,\nN\\sim 196$ is predicted for the first time. In terms of its size in the $(Z,N)$\nplane and the impact of octupole deformation on binding energies this region is\nsimilar to the best known region of octupole deformed nuclei centered at $Z\\sim\n90, N\\sim 136$. For the later island of octupole deformed nuclei, the\ncalculations suggest substantial increase of its size as compared with\navailable experimental data.\n