Molecular Rydberg Transitions. X Correlation Algorithms for Rydberg Term Values

Abstract

The empirical linear correlations of Rydberg term values [S. P. McGlynn, S. Chattopadhyay, P. Hochmann, and H.-t. Wang**, are discussed in a first-order perturbation-theoretic format. In the second-order, quadratic dependencies are expected. The theoretical development assumes that the gross features of interatomic and intermolecular Rydberg term value variations can be discerned using a one-electron model; that a molecule XS, X being the Rydberg chromophore and S the substituent, can be partitioned so that the affairs of the optical electron are dominated by its interactions with the chromophoric segment; and that the charge distributions, whether of X or S, can be expanded in ways which permit evaluation of the effects of small variations in either X or S on Rydberg term values. The development is restricted to Class 1 molecules: Molecules which possess a common S and variable X, but where all X must be of similar electronic structure e.g., X = F, Cl, Br, I). A variety of correlative algorithms is discussed, and the intergroup transferability of parameters is elaborated in terms of the properties of "average chromophores"