Core-particle coupling and polarization effects

The unpaired particle in an odd-mass transitional nucleus exerts forces on the rest of the system leading to an effective shape which is in general dependent on the j-orbital occupied by the extra particle. To account for this polarization effect we propose to modify the collective matrix elements by a phenomenological polarization factor. This enables us to describe also such band structures by the core-particle coupling model for which the common coupling rules seem to fail. Selecting a typical case the model is applied to 123I in order to demonstrate the important role of the polarization. The calculation reproduces fairly well all band structures including their M1 and E2 decay properties. (orig.)