Analysis of electronic correlations in large-angular-momentum states using the Coulomb Green's function: positions of low doubly excited states in alkaline-earth atoms

Abstract

The position of atomic states with an outer electron of large angular momentum l are analysed using a Sturmian expansion of the Coulomb Green's function. The method is applied here to low doubly excited states of alkaline-earth atoms, namely in Ca, in Sr and in Ba. The figures turn out to be as accurate as those from R-matrix theory and may be even better, for example, in strontium. A critical discussion of measured positions is given, completing previously uncertain assignments. New positions for large n are tabulated as well as for previously unreported total angular momentum values. Local series interactions can be analysed and are shown to be weak between two series with an outer g electron.