Anomalous behavior of Auger and radiative rates and fluorescence yields along the $1s2s^22p^{3}$ K-shell isoelectronic sequence*

Calculations using two different methodologies have revealed anomalous behaviour of the radiative and Auger rates, and the associated fluorescence yields, of the six electron $1s2s^22p^{3}$ K-shell vacancy isoelectronic sequence as a function of $Z$ from the neutral to $Z$ of 30. This behavior is explained in terms of an accidental degeneracy, an avoided-crossing of two nearly-degenerate spin-orbit coupled states. The results also demonstrate the importance of including both multielectron correlation and spin-orbit effects even at low- $Z$, and that interpolation of computed fluorescence data is inaccurate in general.