CORRELATION AND RELATIVISTIC EFFECTS FOR 3 3/'-AUTOIONIZATION STATES/

For autoionizing levels converging to the N = 3 threshold of He-like i ons with Z = 3-26, energies and widths obtained Within the generalized diagonalization approach are compared with the results of S-matrix pe rturbation theory. The combined data for the expansion coefficients ca n improve the validity of spectral calculations. Autoionization decay amplitudes and widths are obtained using both unscreened and screened hydrogenic orbitals for the free electron, as well as in the first ord er in continuum Coulomb coupling. Terms of order 1/Z can be extracted to improve the perturbational data for autoionization amplitudes, invo lving both screening corrections and the first-order continuum couplin g. The relative significance of various atomic interactions in evaluat ing autoionization decay amplitudes is discussed.