Charge-Exchange Excitations with Skyrme Interactions in a Separable Approximation

Starting from a Skyrme interaction we propose an extension of the finite rank separable approximation for the case of charge-exchange nuclear modes. This approximation enables one to reduce considerably the dimensions of the matrices that must be diagonalized to perform QRPA calculations in very large configuration spaces. First, we check that the approximation reproduces reasonably well the full charge-exchange RPA results of the spin-dipole resonances in the nuclei 90Zr and 132Sn. The approach is then applied to the study of the Gamow-Teller and the spin-dipole resonances in the neutron-rich Cd isotopes, within the quasiparticle random phase approximation. Subject Index: 210, 213 The study of spin-isospin excitations in neutron-rich nuclei is presently an im-portant problem not only from the nuclear structure point of view but also because of the special role they play in many astrophysical processes. Many fundamental issues depend on our quantitative understanding of phenomena like beta decays o