Spectral representation of the three-body Coulomb problem. II. Autoionizing doubly excited states of unnatural parity in helium

A spectral approach of configuration interaction type is used to evaluate energies and widths for a wide range of singlet and triplet Pe resonance states of helium up to the eighth single ionization threshold. While the present data are in excellent agreement with existing theoretical results (below the N=3-5 ionization threshold) obtained within an explicitly correlated approach, there are substantial differences with the energies, the widths, and the number of resonances obtained with the stabilization method.