Nuclear shape phase transitions

The evolution of shapes and shape (phase) transitions, including regions of short-lived exotic nuclei that are becoming accessible in experiments at radioactive-beam facilities, are governed by the shell structure of single-nucleon orbitals. In most cases the transition between different shapes is gradual but in a number of examples, with the addition or subtraction of only few nucleons, signatures of abrupt changes in observables are noticed. A quantitative analysis necessitates accurate modelling of the underlying nucleonic dynamics. Important advances have been reported in theoretical studies of complex shapes, especially in the 'beyond mean-field' framework based on density functionals. (author)