Abstract
Abstract: In this work we present an algorithm to extract inter-atomic potential of diatomic molecules from spectroscopic data. We construct wave functions and potential functions by B-spline. Various knowledges from the spectra and the intrinsic properties allow us to have a rough form of the inter-atomic potentials. When we have the experiment data. The inter-atomic potential energy curves are then obtained by fitting the calculated vibrational and rotational levels to the experimental spectra. We demonstrate this algorithm by applying to the HeH+ diatomic molecule and the corresponding various isotopes. The flexibility of the B-splines makes it a convenient basis for the representation of the inter-atomic potentials and wave functions. By suitably increasing the density of the knot sequence the B-spline basis set can be used for different diatomic species. We also apply this algorithm to various alkaline-alkaline diatomic molecules. The results presented shows that our algorithm is a convenient approach to obtain the inter-atomic potentials of various diatomic molecules.