Prolate-shape dominance in atomic nuclei within the deformed relativistic

The dominance of prolate over oblate ground-state deformations has been a well-known empirical fact. With the state-of-the-art deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) and taking Te, Xe, and Ba isotopes with neutron number 82 N 126 as examples, a self-consistent and microscopic study of the prolate-shape dominance is given. According to the calculated potential-energy curves, most of these isotopes have both prolate and oblate minima and prefer prolate in the ground state, while the small amount of oblate ground-state shapes mainly appear after the major shell is half filled. It is also found that the prolate-shape dominance enhances with the proton number increasing from 52 to 56. The dominance and its enhancement can be well understood by the microscopic canonical single-particle energies obtained in the DRHBc theory, in good agreement with the schematic interpretation based on the Nilsson diagram. Finally, pairing correlations are found to bring more energy displacements to oblate minima on average but do not play a decisive role in prolate-shape dominance.

Automated summary

Using the state-of-the-art deformed relativistic Hartree-Bogoliubov theory, this study provides a self-consistent and microscopic analysis on the dominance of prolate-shape in Te, Xe, and Ba isotopes with neutron number 82 N 126. The results show that most isotopes exhibit prolate shapes in the ground state, while oblate shapes mainly appear after the major shell is half filled. The dominance of prolate-shape enhances with increasing proton number, and is in agreement with the microscopic canonical single-particle energies obtained in the theory.