DETERMINATION OF DIPOLE POLARIZATION EFFECTS IN LI-7 AND LI-11

The structure of Li-6, Li-7 and Li-11 nuclei is investigated in a model space which includes all configurations with oscillator energy up to 3homegaBAR above the ground-state configuration. The energy spectra and electromagnetic properties of the low-lying states are determined with various two-body interactions, which are derived from the Bonn potential. The results of these shell-model calculations depend on the strength of the tensor component contained in the NN interaction and also on the treatment of the Dirac spinors for the nucleons in the nuclear medium. In addition, the calculation determines the dipole polarizability of Li-7 and Li-11 caused from virtual El excitations to the positive-parity states of these nuclei. It is demonstrated that the BAGEL scheme provides a very powerful tool to consider contributions from virtual excitations up to large energies.