Quadrupole and octupole collectivity and cluster structures in neon isotopes

Abstract

The lowest positive-and negative-parity bands of 20 Ne and neutron-rich even-even Ne isotopes are investigated using a theoretical framework based on energy density functionals. Starting from a self-consistent relativistic Hartree-Bogoliubov calculation of axially-symmetric and reflectionasymmetric deformation energy surfaces, the collective symmetry-conserving states are built using projection techniques and the generator coordinate method. Overall a good agreement with the experimental excitation energies and transition rates is obtained. In particular, the model provides an accurate description of the excitation spectra and transition probabilities in 20 Ne. The contribution of cluster configurations to the low-energy states is discussed, as well as the transitional character of the ground state. The analysis is extended to 22 Ne and the shape-coexisting isotope 24 Ne, and to the drip-line nuclei 32 Ne and 34 Ne. The role of valence neutrons in the formation of molecular-type bonds between clusters is discussed. arXiv:1802.02873v1 [nucl-th] 8 Feb 2018 P J M K denotes the angular momentum projection operator:Pwhere the integral is carried out over the three Euler angles Ω = (α, β, γ), D J M K (Ω) = e −iM α d J M K (β)e −iKγ is the Wigner's D-matrix [32], and the active rotation operator readsR(Ω) = e −iαĴz e −iβĴy e −iγĴz . Good parity quantum number is restored by choosing the reflectionsymmetric basis, that is, by ensuring that for each

Multi-reference many-body perturbation theory for nuclei II -- Ab initio study of neon isotopes via PGCM and IM-NCSM calculations

“…The above results are qualitatively very similar to those obtained through relativistic multi-reference energy density functional (MR-EDF) calculations [46,48]. While being also quantitatively close, the present ab initio calculation produces more rigid TES than the EDF ones, especially on the oblate side.…”

“…The present study focuses first on the stable 20 Ne isotope. This nucleus has been extensively studied experimentally and theoretically in the past [46,47], in part because it is one of the few nuclei displaying a strong admixture of cluster configurations in the ground state. The ab initio description of this doubly open-shell nucleus is thus a challenge given that it is necessary to appropriately capture both dynamical and static correlations.…”

“…The interpretation of these features in terms of molecular covalent bonds is developed in Ref. [48]. that is obviously due to missing dynamical correlations.…”

Microscopic core-quasiparticle coupling model for spectroscopy of odd-mass nuclei with octupole correlations

“…In the following the superscript A ± 1 will be omitted for convenience. In this particular study we will calculate the input for the CQC model using an axially reflection-asymmetric implementation of the relativistic Hartree-Bogoliubov (RHB) model [29], combined with the quadrupole-octupole collective Hamiltonian [52]. The RHB model provides a unified description of particle-hole (ph) and particle-particle (pp) correlations on a mean-field level by combining two average potentials: the self-consistent mean field that encloses long range ph correlations and a pairing field∆ which sums up pp correlations.…”

Low-energy monopole strength in spherical and deformed nuclei : cluster and soft modes

“…Recently, relativistic EDFs were shown to consistently describe both liquid-and cluster-like features of nuclei, be it their ground-state [30][31][32][33][34] or spectroscopic (energies of excited states, reduced probability transition, elastic and inelastic form factors, etc.) properties [35,36]. Since a covariant formulation of the quasiparticle random phase approximation (QRPA), is known to correctly describe GRs and soft modes [21,23,[37][38][39][40][41][42][43] on one hand, as well as cluster vibrations [14] on the other, it shall be a tool of choice for achieving a global understanding of the mechanisms driving the emergence of these modes.…”