Considering that the IBM and IBFM cranking calculations in the lowest order of angular frequency can give reasonably good estimates for the moment of inertia, we extend them to study the dependence of the moment of inertia on the higher order terms. We find that the analytic expressions for the correction terms can be derived. Numerical calculations for ~(154)Gd and ~(161)Er are performed and compared with experiment. The Hamiltonian is taken from a microscopic approach. Calculated results show that the properties of higher order terms depend on the deformation of rotating ...
