Octupole correlations in the ${}^{144}\mathrm{Ba}$ nucleus described with symmetry-conserving configuration-mixing calculations

We study the interplay of quadrupole and octupole degrees of freedom in the structure of the isotope ${}^{144}\mathrm{Ba}$. A symmetry-conserving configuration-mixing method (SCCM) based on a Gogny energy density functional (EDF) has been used. The method includes particle number, parity, and angular momentum restoration as well as axial quadrupole and octupole shape mixing within the generator coordinate method. Predictions both for excitation energies and electromagnetic transition probabilities are in good agreement with the most recent experimental data.

Figure 1

HFB potential energy surface in the $({\beta }_2,{\beta }_3)$ plane normalized to the energy of the minimum ($-1180.772$ MeV with eleven HO shells) computed for ${}^{144}\mathrm{Ba}$ with the Gogny D1S parametrization. Contour lines are separated by 0.5 MeV (dashed lines) and 2.0 MeV (full lines) respectively. White dashed (dotted) lines represent the paths for one-dimensional ${\beta }_2 \left({\beta }_3\right)$ constrained HFB calculations. The spatial density of the HFB ground state is also plotted.

Figure 2

Particle number, parity, and angular momentum PES in the $({\beta }_2,{\beta }_3)$ plane normalized to the energy of the minimum of the $0^{+}$-PES ($-1185.600$ MeV with eleven HO shells). Contour lines are separated by 0.5 MeV (dashed lines) and 2.0 MeV (full lines) respectively.

Figure 3

Spectra (first two bands) obtained from SCCM calculations with (a) ${\beta }_2$, (b) ${\beta }_3$, and (c) ${\beta }_2-{\beta }_3$ as generating coordinates for ${}^{144}\mathrm{Ba}$. Experimental data (d) are taken from Ref. [36].

Figure 4

Collective wave functions for the ground state (upper part) and first excited negative-parity (lower part) bands.