Calculation and evaluation of energy levels and radiative rates for and transitions in Cu XX

Energy levels, oscillator strengths, and radiative rates have been calculated for 2 s 2 2 p 6 – 2 s 2 p 6 n p and 2 s 2 2 p 6 – 2 s 2 2 p 5 n d transitions with 4 ≤ n ≤ 20 in Cu XX ions. In the calculations, the Flexible Atomic Code has been used, and systematic analysis and evaluation of the accuracy of the calculated results for the two types of transitions are also given with different indicators. It is shown that the results for the transitions with a 2 s hole are greatly improved by using the present method comparing to those from RELAC code. Furthermore, our results show that the energy levels of the 2 s 2 p 6 ( n + 1 ) l and 2 s 2 2 p 5 ( n + 2 ) l configurations closely interact with those of the 2 s 2 p 6 n p series and it is essential to include the 2 s 2 2 p 5 ( n + 1 ) l configurations in the calculations for the 2 s 2 2 p 5 n d series.