Theoretical Confirmation of the Low Experimental 3C/3D f-Value Ratio in Fe xvii.

Radiative transition probabilities (A values) are computed for the Fe xvii L-shell lines in a Breit-Pauli configuration-interaction method with the autostructure atomic structure code. It is shown that, by carefully taking into account the fine-tuning of the relativistic coupling and 2p-orbital relaxation, the measured A values of the M1 and M2 lines and, for the first time, the low f(3C)/f(3D) oscillator-strength ratio are satisfactorily reproduced by the theory. The present ratio f(3C)/f(3D)=2.82 compares well with the measurement of 2.61±0.23 by x-ray laser spectroscopy.