Coexistence of Cluster States and Mean-Field-Type States

Abstract

In this lecture I first review present knowledge about the actual coexistence features of cluster states and mean-field-type states in nuclei. I then discuss how nuclear structure changes from shell-model-like ground state to cluster states. About the actual coexistence features I review them in two parts. In the first part I discuss 8Be, 12C, 16O, and 20Ne. In the second part I discuss 44Ti and 32S where superdeformed atates are observed. The investigation in 32S suggests strong interrelation of 16O + 16O molecular states and superdeformed states. For the discussions of 20Ne, 44Ti and 32S systems, I utilize the results of the detailed studies with antisymmetrized molecular dynamics (AMD). On the basis of these studies of actual coexistence features, I discuss the mechanism of the structure-change between cluster structure and mean-field-type structure and indicate that it comes from the dual nature of nuclear wave functions which have both characters of cluster wave function and mean-field-type wave function. Observed strong E0 transitions between cluster states and the ground state are explained to be a good verification of dual nature of nuclear wave function.