Octupole Deformation in Atomic Nuclei: Challenges and Progress with Large-Scale Shell Model Calculations

Experiments with atoms or molecules containing nuclei that exhibit octupole deformation have significantly improved the limits on the time-reversal violation. Compared to quadrupole deformation, however, octupole deformation is much less explored due to the need for large model spaces in microscopic calculations. To identify even-even nuclei that are unstable or soft against octupole deformation, we use self-consistent mean-field theory. We follow up with large-scale shell-model calculations to explore in detail the low-lying octupole response of selected nuclides, laying the groundwork for further investigations into octupole degrees of freedom.