Long-range components of the effective nucleon-nucleon interaction

We discuss two simple effective interactions which fit selected empirical (j2)/sub T/ matrix elements. One important property of both interactions is the presence of a long range repulsion in odd states, as was already pointed out previously by others. We then discuss the role of configuration mixing in both the weak coupling and strong coupling limits to show qualitatively that the repulson can arise naturally from truncation of the model space used to define the interaction. Presumably with a sufficiently larger model space no long range repulsion is needed. We also remark on the difference between yrast state energies and centroids of the single particle transfer strength. It is the latter which are based in the empirical matrix elements. Finally we briefly discuss a semiclassical model for calculating matrix elements for a finite range interaction