Collective and Interparticle Interactions in Even-Even Nuclei

A calculation using two equivalent f7/2 particles and adding surface effects to the two-body interaction is reported. The effects of increasing the strength of (a) the surface interaction and (b) the two-particle interaction are computed. The qualitative regularities observed in even-even nuclei in the so-called vibrational region are obtained and the agreement is somewhat better than that with the pure vibrational model. In contrast to earlier calculations, these results can give a spin of 2⁺ for the second excited state, as often observed. The calculated ratio of B(E2; 2^'→2) to B(E2; 2→0) is less than 1.0. The appropriate values of the deformation parameters x are less than 1.0.