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

Abstract

A systematic investigation of octupole deformed nuclei is presented for even-even systems with Z ≤ 106 located between the two-proton and two-neutron drip lines. For this study we use five most up-to-date covariant energy density functionals of different types, with a non-linear meson coupling, with density dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov (RHB) theory based on an effective separable particle-particle interaction of finite range. This allows us to assess theoretical uncertainties within the present covariant models for the prediction of physical observables relevant for octupole deformed nuclei. In addition, a detailed comparison with the predictions of non-relativistic models is performed. A new region of octupole deformation, centered around Z ∼ 98, N ∼ 196 is predicted for the first time. In terms of its size in the (Z, N ) plane and the impact of octupole deformation on binding energies this region is similar to the best known region of octupole deformed nuclei centered at Z ∼ 90, N ∼ 136. For the later island of octupole deformed nuclei, the calculations suggest substantial increase of its size as compared with available experimental data.

Tetrahedral shapes of neutron-rich Zr isotopes from a multidimensionally constrained relativistic Hartree-Bogoliubov model

“…[21], i.e., G n = G p = 1.12G 0 with G 0 = 738 MeV·fm 3 , we can get the same results as Ref. [21]. When the β 32 deformation is allowed in the calculations, both axial and reflection symmetries are broken.…”

“…In these studies, the coexistence of prolate and oblate minima in potential energy curves of even-even Zr isotopes were discussed. By including the β 30 deformation, a pear-like ground state of 112 Zr is predicted with the functional DD-PC1 [21]. From the experimental point of view, the analysis of rotational bands, β-decay half-lives, and lifetimes of the first 2 + states reveals that some of these nuclei are well deformed [62,[152][153][154][155][156][157][158][159][160][161][162][163][164] Next we give some numerical details and illustrative calculations of the MDC-RHB model.…”

“…[18] for a review. The pear-like nuclear shape, characterized by β 30 , was predicted to be very pronounced in many nuclei [19][20][21]. Low-lying negative-parity levels which are connected with the ground state band via strong E1 transitions in actinides and some rare-earth nuclei are related to reflection asymmetric shapes with nonzero β 30 [22][23][24][25][26][27][28][29][30][31].…”

Spectroscopy of reflection-asymmetric nuclei with relativistic energy density functionals

“…The RHB model with the finite-range separable pairing force was successfully used in the description of octupole deformations [38] and low-energy excitation spectra [33]. DES exhibits a global minimum at (β 2 , β 3 ) = (0.18, 0.14), and is rather soft along the octupole direction.…”

Recent Progress in the Studies of Neutron-rich and High-$Z$ Systems Within the Covariant Density Functional Theory

“…These studies cover the properties and related systematic uncertainties of different physi-cal observables for all even-even nuclei with Z ≤ 106 [12,13], for the position of the two-neutron drip line [12,13,14], for octupole deformed [15] and superheavy nuclei [16]. Note that the analysis of theoretical uncertainties has also been performed in Skyrme DFTs in Refs.…”