Taking the effect of variation of moment of inertia with angular momentum “concept of softness", and a harmonic variable moment of inertia model "AVM", a new formula is obtained, denoted AVNS. The AVNS model is used in calculating the energies of rotational ground bands of Sm150, Sm152, Gd154, Os192, Pt186, Pt182 and Yb158 nuclei. The predicted results of the AVNS are in close agreements with AVM calculations and experimental data.