Systematic investigation of diabatic correlations

Abstract

With the aim to investigate systematically diabatic correlations, a series of adiabatic molecular-orbital correlation diagrams for quasimolecular systems ranging from Ne + Ne to Xe + Xe is generated from the variable-screening model and subsequently analyzed. The novel feature of the diagrams for both symmetric and asymmetric systems is the appearance of numerous pseudocrossings which hitherto have not been incorporated into the standard qualitative diabatic correlation diagrams. An analysis of these additional crossings leads to the formulation of an empirical, new rule for diabatic correlations, which is stated in two equivalent forms and which should, under certain conditions, replace the rule given by Barat and Lichten. By a study of perturbations which screening effects impose on a Coulombic quasimolecular system, the conditions of validity of the "old" and the "new" rule can be qualitatively clarified. Experimental consequences of the new rule are briefly discussed.