Comparison of the relative accuracy of the potential energy curve of hydrogen fluoride from ab initio calculations and from an empirical “universal” function

The accuracy of recent theoretical calculations of the potential energy curve of hydrogen fluoride is compared to that of the potential predicted by a previously proposed empirical Morse-like function, universally applicable to stable ground state diatomics. In addition to the properties required for the Morse equation (bond energy, bond length, vibrational frequency, and mass) two more properties are used by the empirical function: the electronegativity difference and the product of Slater's effective nuclear charges of the two atoms. Eigenvalues obtained from the most successful of recent ab initio calculations and from the empirical function are compared to experimental vibrational term values, as a stringent test of accuracy. The accuracy of the empirical “universal” function is marginally superior.