Microscopic description of band structure at very extended shapes in the A∼110 mass region

Recent experiments have confirmed the existence of rotational bands in the A∼110 mass region with very extended shapes lying between super- and hyperdeformation. Using the projected shell model, we make a first attempt to describe quantitatively such a band structure in ¹⁰⁸Cd. Excellent agreement is achieved in the dynamic moment of inertia I⁽²⁾ calculation. This allows us to suggest the spin values for the energy levels, which are experimentally unknown. It is found that, at this large deformation, the sharply down-sloping orbitals in the proton i_13/2 subshell are responsible for the irregularity in the experimental I⁽²⁾, and the wave functions of the observed states have a dominant component of two-quasiparticles from these orbitals. Measurement of transition quadrupole moments and g factors will test these findings, and thus can provide a deeper understanding of the band structure at very extended shapes.