Development and evolution of deformation in medium-heavy nuclei
The development of regions of nuclear deformation far from the valley of stability is a result of the interplay between the central nuclear field and the quadrupole force. When quadrupole correlations dominate, the use of dynamical symmetries based on the SU3 symmetry of Elliott can be of help both to estimate the leading configurations at low excitation energy and the optimal model space that allow the relevant degrees of freedom in microscopic shell model calculations. This allows to interpret the different observables and understand the underlying processes and to make predictions on the development of deformation in different mass regions. After a brief introduction to the quasi and pseudo SU3 dynamical symmetries, base on a recent work, a review on different investigations at the islands of inversion will be given. This will cover both ground-state properties and excited states along several isotopic chains.