Energies and interelectronic angle in doubly excited 1Se states of helium-like ions below the N = 2, 3 and 4 hydrogenic thresholds

Doubly excited 1Se states of helium-like ions (Z=2-10) converging on the N=2, 3 and 4 hydrogenic thresholds are studied by a method of stabilization using correlated Hylleraas-type wavefunctions and a real Hamiltonian. Total energies, kinetic and Coulomb energies and the cosine of the interelectronic angle of the two electrons are calculated. Results obtained show quantitatively the correlation effects in the doubly excited intrashell states and demonstrate how the expectation values of the cosine of the interelectronic angle of the two electrons depend on details of the dynamics