Octupole correlations in the nucleus 144Ba described with modern microscopic techniques

Octupole correlations are described in a microscopic framework involving angular momentum, parity and particle number projected intrinsic Hartree–Fock–Bogoliubov states. Linear combinations of those symmetry restored states are considered to account for collective positive and negative parity states in the nucleus ¹⁴⁴Ba. The well-known Gogny D1S interaction is used in the calculations. A strong octupole collectivity is observed in the negative parity states justifying the assignment of ¹⁴⁴Ba as an octupole deformed nucleus. Higher lying excited states are studied and its structure is identified by looking at the collective wave functions obtained in the calculations. An oblate-spherical 0⁺ shape isomer and a two-phonon octupole multiplet are described in detail.