Octupole correlations of the <i> K _π </i> = 5/2 ⁺ ground-state band in ²²⁹ Th

Abstract The octupole correlations of the K π = 5/2 + ground state and the rotational spectrum built on it in 229 Th 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 229 Th 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 ( E 2) and B ( M 1), are reasonably well reproduced.