The Nuclear Shape Phase Transitions Studied within the Geometric Collective Mode

In the framework of the Geometric Collective Model (GCM), quantum phase transition between spherical and deformed shapes of doubly even nuclei are investigated. The validity of the model is examined for the case of lanthanide chains Nd/Sm and actinide chains Th/U. The parameters of the model were obtained by performing a computer simulated search program in order to obtain minimum root mean square deviations between the calculated and the experimental excitation energies. Calculated potential energy surfaces (PES’s) describing all deformation effects of each nucleus are extracted. Our systematic studies on lanthanide and actinide chains have revealed a shape transition from spherical vibrator to axially deformed rotor when moving from the lighter to the heavier isotopes.