Atomic data for opacity calculations. XIV. The beryllium sequence

Abstract

The authors have calculated 1814 energy levels in LS coupling, 33030 oscillator strengths and 859570 photoionization cross section values for the following fifteen members of the beryllium isoelectronic sequence: Be I, B II, C III, N IV, O V, F VI, Ne VII, Na VIII, Mg IX, Al X, Si XI, S XIII, Ar XV, Ca XVII and Fe XXIII. Photoionization is from 1554 bound states lying below the 2s ionization thresholds. The continua are perturbed by resonances converging onto the 2p, 3s, 3p and 3d states of the residual Li-like ions. They delineate the resulting autoionization features by using sufficiently small energy step lengths in regions where the cross sections vary rapidly. Photoexcitation of the core produces large PEC resonances which dominate photoionization of Be I and the less highly ionized ions. They discuss some selected examples drawn from the entire data set and make comparisons with the work of other investigators.