Modified Kratzer-Fues Formula for Rotation-Vibration Energy of Diatomic Molecules

An extension of the Kratzer-Fues approach to analytical calculation of the rotation-vibration energy of diatomic molecules is proposed. The eigen-values from this approach are applied in calculation of the rotational and rovibrational energies and in evaluation of molecular constants of selected diatomic molecules, resulting in satisfactory reproduction of experimental frequencies over a wide range of rotational states. In contrast to our previous proposition the rotational dependence of vibration energy is taken into account. An additional set of fitted parameters which include equilibrium distance and dissociation constant was also employed.