Empirical quality criteria for the approximation of the electronic term of a diatomic molecule by the Morse formula

Abstract

A brief review of the latest results of the application of the approximation of the potential of a diatomic molecule by the Morse model function in applied spectroscopy is presented. The functions of the electronic terms of the diatomic molecules BeH, F2, H2, HCl, and Be2 are compared with their two alternative approximations by the Morse function. As a criterion, we used the differences between the original (approximated) term and its Morse models, which, combined with the dependence of the anharmonicity of the original terms on the vibrational quantum number ωexe(v), allowed to formulate some generalizations about the deformation of the form the original term in the approximations. Simulation always leads to an increase in the bond energy in the range of 7-50% and to an increase in the number of vibrational levels. In favorable cases, the contour shape is reproduced with a deviation of no more than 100-200 cm-1 in the lower part of the potential well. Key words: Morse formula, diatomic molecule, anharmonicity, electronic terms, vibrational structure.