Configuration interaction effects on the energy levels and oscillator strengths of lowly charged gold ions: Au11+ as an example

The effects of configuration interaction (CI) on the energy levels and oscillator strengths of Au11+ have been investigated by systematically adding configurations included in calculations. Four sets of calculations, namely, a single configuration Dirac-Fock type, CI with singly, doubly, and triply electron excitations from the ground configuration of Au11+ have been carried out to show the effects. The results show that CI not only affects distribution of the oscillator strengths among one transition array, but also affects the distributions among different transition arrays. For example, the converged oscillator strengths for transition arrays of 5p→5d (e.g. 5p6→5p55d and 5p55d→5p45d2) are greatly reduced compared with the results of single configuration approximation. On the other hand, for transition arrays of 4f→5d (e.g. 5p6→4f135d and 5p55d→4f135p55d2), the converged oscillator strengths are drastically enhanced. The CI effects result in the net transfer of oscillator strengths from transition arrays of 5p→5d to 4f→5d.