Description of low-lying collective states in osmium isotopes in the boson expansion theory

The low-lying collective states in osmium isotopes are investigated microscopically by means of the boson expansion theory with the self-consistent effective interactions. The potential energy surfaces and the structures of boson wave functions are illustrated. Theoretical level structures and electromagnetic properties are compared with the available experimental data. The prolate-oblate shape transition predicted at around N = 116 is also discussed in terms of the evolution of the theoretical potential as the neutron number changes.