Comments on the paper 'Comparison study of bound states for diatomic molecules using Kratzer, Morse, and modified Morse potentials'

Al-Othman et al (2022, Phys. Scr. 97 035401) in their paper have compared the energy eigenvalues obtained using Kratzer, Morse, and modified Morse potentials for four diatomic molecules (H-2, N-2, CO, and HCl) using the shifted 1/N expansion method. We show that due to the wrong expression of the parameter used in the modified Morse potential, the energy eigenvalues obtained for the case of modified Morse potential are incorrect, and the interpretation of the results stated in this paper is not reliable. We have rectified the error and recalculated the vibrational energy eigenvalues for the ground state of the HCl molecule using the shifted 1/N expansion method and compared the accuracy of Kratzer, Morse, and modified Morse with that of the observed vibrational energy eigenvalues. Also, we have determined the energy eigenvalues for the ground state of the HCl molecule by numerically solving the Schrodinger equation for the case of the modified Morse potential and compared the accuracy with the values obtained using the shifted 1/N expansion method. The vibrational energy eigenvalues obtained using modified Morse for the HCl molecule are found to be closer to the observed values than the Morse and Kratzer potential functions.