Approximate non-relativistic energy expression and the rotational-vibrational constants of the Tietz-Hua potential: a semiclassical approach

The low- and high-lying rovibrational energy levels of the Schrodinger equation with the molecular Tietz-Hua potential are obtained via the Wentzel-Kramers-Brilluoin (WKB) quantization approach. The Pekeris-type approximation scheme is applied to deal with the orbital centrifugal term of the effective potential function. The obtained energy spectra and the rotational-vibrational (rovibrational) coefficients for N-2(X-1 Sigma(+)(g)), (O2+X2)Pi(+)(g)), H-2(X-1 Sigma(+)(g)), and HF(X-1 Sigma(+)) diatomic molecules were compared with the ones obtained by other analytical methods and available experimental data in the literature. The results revealed that the accuracy of the energy spectra for the high-lying rovibrational quantum states may depend on the rotational-vibrational constants.