Octupole correlations of the K_π = 5/2⁺ ground-state band in ²²⁹Th

The octupole correlations of the K^π = 5/2⁺ ground state and the rotational spectrum built on it in ²²⁹Th are studied using the microscopic relativistic density functional theory on a three-dimensional lattice space and the reflection-asymmetric triaxial particle rotor model. It is found that ²²⁹Th has a ground state with static axial octupole and quadrupole deformations. The occurrence of octupole correlations, driven by the octupole deformation, is analyzed through the evolution of single-particle levels around the Fermi surface. The experimental energy spectrum and the electromagnetic transition probabilities, including B(E2) and B(M1), are reasonably well reproduced.