Relativistic mean-field description of small- and large-amplitude collective motion in nuclei

Abstract

The dynamics of collective motion in nuclei is described in the framework of time-dependent relativistic mean-field theory. For a given set of initial conditions (stationary solution for the ground state, initial velocities of the proton and neutron densities, initial deformations), the model describes the time evolution of the nuclear system. In the limit of small-amplitude motion we investigate isovector dipole, isoscalar quadrupole, and isovector quadrupole oscillations. Model calculations are performed for the nuclei 16O, 40Ca, 48Ca and compared with experimental data on energies and widths of giant resonances. For 48Ca we also investigate the dynamics of large-amplitude isovector dipole motion. With increasing excitation energy the motion becomes strongly anharmonic and clusters of particles evaporate from the surface of the nucleus. At the highest energies we find a rapid dissociation of the nucleus in proton and neutron clusters.