Variable moment of inertia in the interacting boson model

We present a simple prescription for the determination of the nuclear softness parameter, a measure of low-spin variation of the moment of inertia, in the interacting boson model. The formulation makes use of explicit dependence of the moment of inertia on the d-boson mixing parameter. The systematics of the softness parameter are carried out using an effective interacting boson model Hamiltonian approach and results are found to be in excellent agreement