Representing Potential Energy Functions by Expansions in Orthogonal Polynomials. Generalized SPF Potentials

It long has been known that advantages attend employing, as a basic internuclear coordinate for determining a molecular potential energy surface, a variable S = 1 − R 0/R, where R 0 is a reference distance near to half of an equilibrium distance. For a diatomic molecule, starting from numerical or analytical representations of the energy, W(R) = W(S), it is shown how to generate the analytical series, W(S) = σ(S)∑ n b n P n (S), where P n (S) …