RELATIVISTIC MEAN-FIELD DESCRIPTION OF SMALL-AMPLITUDE AND LARGE-AMPLITUDE COLLECTIVE MOTION IN NUCLEI

The dynamics of collective motion in nuclei is described in the framew ork of time-dependent relativistic mean-field theory. For a given set of initial conditions (stationary solution for the ground state, initi al velocities of the proton and neutron densities, initial deformation s), the model describes the time evolution of the nuclear system. In t he limit of small-amplitude motion we investigate isovector dipole, is oscalar quadrupole, and isovector quadrupole oscillations. Model calcu lations are performed for the nuclei O-16, Ca-40, Ca-48 and compared w ith experimental data on energies and widths of giant resonances. For Ca-48 we also investigate the dynamics of large-amplitude isovector di pole motion. With increasing excitation energy the motion becomes stro ngly anharmonic and clusters of particles evaporate from the surface o f the nucleus. At the highest energies we find a rapid dissociation of the nucleus in proton and neutron clusters.