Relativistic Calculation of 2p53s, 3pand 3dEnergy Levels and Transition Wavelengths in Ti XIII, Fe XVII and Some Other Neon-Like Ions

Average energies for the configurations 2 p 5 3 s , 3 p and 3 d in a number of neon-like ions from Al IV to Xe XLV have been calculated by means of the MCDF computer code of Grant et al. The results have been compared with observations and previous non-relativistic calculations. Fine-structure levels and 3 s -3 p and 3 p -3 d transition wavelengths have also been calculated with the MCDF code for Ti XIII and Fe XVII, both in the single-configuration approximation and in a multiconfiguration treatment including 2 s 2 p 6 nl . The configuration interaction was found to affect 2 p 5 3 p 3 S 1 most seriously. A separate optimization for the 3 p 1 S 0 state was needed, due to the particular radial dependence of this state. The calculated wavelengths show excellent agreement with the observations, and the MCDF calculations are well suited for wavelength predictions in neon-like n = 3 systems.