Evolution of ground-state quadrupole and octupole stiffnesses in even-even barium isotopes.

Quadrupole and octupole stiffnesses in the ground states of even-even 112-150Ba isotopes have been systematically investigated by means of potential-energy-surface calculations. The calculations are carried out in both (β2,γ,β4) and ((β2, (β3, (β4, (β5) deformation spaces with the inclusion of triaxial and reflection-asymmetric shape degrees of freedom, respectively. The present results are compared with previous calculations and available experiments. The shape instabilities are evaluated by analyzing the potential energy curves with respect to both the quadrupole and octupole deformations, which is consistent with the previous discussions predicting the γ softness or triaxiality and octupole instability. In addition, taking the near-drip-line 114Ba nucleus as an example, we briefly investigate the effects of potential parameters (e.g., the strength of the spin-orbit potential λ, and the nuclear surface diffuseness a) on the deformation energy curve, showing almost negligible modifications of nuclear shape and stiffness but considerable changes in the depth of the minimum and the height of the fission barrier (which may be very important for the study of heavy and superheavy nuclei). [ABSTRACT FROM AUTHOR]