Abstract
In this paper, an interacting boson model (IBM-1) has been used to calculate the low-lying positive parity yrast bands in Hf, W, and Os nuclei for N = 108 neutrons. The systematic yrast level, electric reduced transition probabilities B(E2)down arrow, deformation, and quadrupole moments of those nuclei are calculated and compared with the available experimental values. The ratio of the excitation energies of first 4(+) and first 2(+) excited states, R-4/2, is also studied for these nuclei. Furthermore, as a measure to quantify the evolution, we have studied systematically the yrast level R = (E2 : L+ -> (L - 2)(+))/(E2 : 2(+) -> 0(+)) of some low-lying quadrupole collective states in comparison to the available experimental data. The associated quadrupole moments and deformation parameters have also been calculated. Moreover, we have studied the systematic B(E2) values, intrinsic quadrupole moments, and deformation parameters in those nuclei. The moment of inertia as a function of the square of the rotational energy for even atomic numbers Z = 72, 74, 76 and N = 108 nuclei indicates the nature of the back-bending properties. The results of these calculations are in good agreement with the corresponding available experimental data. The analytic IBM-1 calculation of yrast levels and B(E2) values of even-even Hf, W, and Os for N = 108 nuclei were performed in the SU(3) character.