[en] A systematic study of ground state band (yrast band) in even-even isotopes has been considered. Back bending phenomenon and the displacement of the odd spin states relative to their even spin neighbors in gamma vibration bands in each isotope as a function of nuclear spin I values as well as neutron number. The decoupling factor A₂k and moment of inertia of rotational sequences are also studied. The deviations from a regular rotational sequence are attributed to band crossing. Our results are in good agreement with recent theoretical and experimental data