Use of Pade approximants in the construction of diabatic potential energy curves for ionic molecules

For most ionic molecules, sufficient experimental information is not available for the construction of an RKR potential curve; thus, model potentials have been employed which use some of the experimental information in their construction (e.g., Born-Mayer and Rittner potentials). In this paper, we present a simple method for constructing model potential curves which allows one to use all the available experimental information and to easily incorporate new information as it becomes available. This method, employing a Padé approximant technique, is capable of predicting the value of higher Dunham coefficients to within experimental accuracy from a knowledge of the lower ones. Consequently, it also predicts some spectroscopic properties from a knowledge of other data to much better accuracy than the Rittner or Born-Mayer models.