SPECIAL SOLUTIONS OF THE BOHR HAMILTONIAN RELATED TO SHAPE PHASE TRANSITIONS IN NUCLEI

Nuclei exhibit quantum phase transitions (earlier called ground state phase transitions) between different shapes as the number of nucleons is modified, resulting in changes in the ground and low lying nuclear states. Special solutions of the Bohr Hamiltonian appropriate for the critical point of such shape phase transitions, as well as other special solutions applicable to relevant nuclear regions are described.