Abstract : A simple, four-parameter algebraic collective model (ACM) Hamiltonian is used to describe 166Er. In this nucleus anharmonic double-γ vibrations are observed and the third excited 0+ state has been identified as a candidate for a bandhead of a β band. In contrast to γ-vibrational bands, systematically observed in deformed nuclei, β-vibrational bands are rarely well realized in nuclei and their observation and interpretation is still far from satisfactory. The purpose of the present paper is to show how the ACM model is capable to address complex properties of deformed nuclei in this region and what are its successes and weak points.
