Ground-state and stability properties of [formula omitted] isotopes based on semi-microscopic calculations

Abstract

In this study, we present theoretical predictions on the stability properties of the yet unknown Og118276−293,295−308 isotopes using the Skyrme-SLy4 nucleon–nucleon interaction and the deformed Woods–Saxon single-particle potential in a semi-microscopic approach. The ground-state masses, binding energy, deformations and fission barriers are calculated from the total energy surfaces produced in a multidimensional deformation space using the dynamical differential evolution optimization method. Besides, the Q-values of the different decay modes and the nucleon separation energies for each isotope, and its α-decay (Tα) and spontaneous fission half-lives are also calculated. Our study revealed the Og290−296 elements to be the most bound Oganesson isotopes, among which 302,304,306Og elements are predicted to be spherical nuclei, and 299,300,301,303,305Og elements are shown to be almost spherical. The predicted ground-state and decay properties successfully reproduced the available data of the solely known Oganesson isotope 294Og. In addition to the principle α-decay modes, we studied the rival decay modes that challenge the stability of nuclei in the superheavy regions, namely the electron capture β+ decays and the spontaneous fission. An overall oscillating increasing behavior of Tα with the mass number is obtained, which obviously reverses the hesitating decreasing behavior of Qα and follows increasing trend of the corresponding change in the neutron-skin thickness after α-decays. The Og291,294−296,299−302 isotopes are expected to have relatively long half-lives, Tα≈ 1–45 ms, while 295Og is found to have the longest half-life between the considered nuclei. The Og291−300 isotopes exhibited relatively high fission barriers and small branching ratios for their spontaneous fission modes.