The love-hate relationship between the shell model and cluster models

We adopt a personal approach here reviewing several calculations over the years in which we have experienced confrontations between cluster models and the shell model. In previous cluster conferences, we have noted that cluster models go hand in hand with Skyrme-Hartree-Fock calculations in describing states which cannot easily, if at all, be handled by the shell model. These are the highly deformed (many particle-many hole) intruder states, linear chain states, etc. In the present work, we will consider several topics: the quadrupole moment of ⁶Li; the nonexistence of low-lying intruders in ⁸Be; and then jumping to the f _7/2 shell, we discuss the two-faceted nature of the nuclei, which sometimes display shell-model properties and other times cluster properties.