EFFECT OF POSITIVE-ENERGY ORBITALS ON THE PHOTOIONIZATION CROSS-SECTIONS AND OSCILLATOR-STRENGTHS OF HE AND DIVALENT ATOMS

The effect of the positive-energy continuum orbitals to the photoioniz ation and bound-bound transitions in He and Mg-like divalent Al+ ion i s estimated quantitatively in a B-spline-based configuration-interacti on calculation. Our calculation has also shown that the theoretical un certainty in radiative lifetimes measured in terms of the difference b etween the length and velocity results, due to the use of a parametriz ed long-range dipole core-polarization potential, is approximately 1-3 % for the Mg-like divalent Al+ ion.