Energy and isospin dependence of nuclear chaos - art. no. 014311

Energy levels and wave functions, obtained in realistic shell-model calcula tions for Ca and Sc isotopes up to A=52 and Ti-46, are analyzed using stand ard statistics such as the nearest level spacing distribution, the Dyson-Me hta Delta (3) and the mean localization length. These statistics are calcul ated for different energy regions of the spectrum. For all the Ca isotopes, in the ground state region the energy levels show strong deviations from G aussian orthogonal ensemble predictions. It is shown that a transition to a more chaotic regime takes place as excitation energy increases. However, e ven when the full spectrum is taken into account, the Delta (3), and the de gree of localization of the eigenfunctions in the mean-field basis prove th at Ca isotopes are less chaotic than Sc isotopes. A comparison with Ti-46 s hows that this nucleus is still more chaotic. Thus we find a clear isospin dependence in the degree of nuclear chaoticity.