Energies, fine structures and oscillator strengths of 1s22p21S,1D and3P2,1,0states of Be-like ions

The energies and wave functions of the 1s 2 2p 2 1 S, 3 P and 1 D states are calculated with a full-core plus correlation method (FCPC) for ions from B II to Ne VII, Mg IX and Si XI. A restricted variational method is used to extrapolate a better nonrelativistic energy. The relativistic correction and fine structures are calculated with first-order perturbation theory. Higher order effects are estimated. The oscillator strengths for 1s 2 2s n p ( n = 2, 3) 1 P o –1s 2 2p 2 1 S, 1 D and for 1s 2 2s n p ( n = 2, 3) 3 P o –1s 2 2p 2 3 P are calculated. The results are compared with available theoretical and experimental data in the literature. The excitation energies predicted in this work are slightly higher than the precision experiment. For example, for 1 D, it is higher by 8.5 cm −1 for Z = 4 and the discrepancy increases to 149 cm −1 for Z = 14. The dipole-length, -velocity and -acceleration oscillator strengths calculated in this work agree well with each other. However, some discrepancies still exist between the predicted oscillator strengths and experiment.