Abstract
The rotational and vibrational energies and the electric transition probability B (E2) of the even-even Th228-232 isotopes are studied empirically in framework of a nuclear phenomenological approach by using the SU(3) dynamical symmetries of the Interacting Boson Model-1 (IBM-1). Furthermore, the potential energy surfaces for these isotopes are plotted as functions of the deformation parameters beta and gamma. Moreover, we introduce empirical fit formulas for rotational and vibrational energies, which used to calculate these energies for the thorium isotopes. The obtained results by applying the IBM-1 and the authors' formulas are in good agreement with the corresponding experimental data for most of the nuclear states.