Classification of doubly excited states of two-electron atoms

Based upon the analysis of electron correlations in hyperspherical coordinates, a classification scheme for all doubly excited states of two-electron atoms is presented. A new set of correlation quantum numbers, K, T, and A, is introduced, where (K,T) describes angular correlations and A describes radial correlations. It is shown that states with different L, S, and π but identical (K,T)/sup A/ have isomorphic correlations. Such isomorphism is shown to result in the general supermultiplet structure of doubly excited states