Nonmonotonic behavior as a function of nuclear charge of the K-shell Auger and radiative rates and fluorescence yields along the 1s2s(2)2p(3) isoelectronic sequence

Calculations using multiconfiguration Breit-Pauli and multiconfiguration Dirac-Fock methodologies have revealed that the radiative and Auger rates, and the associated fluorescence yields, of the six electron 1s2s(2)2p(3) K-shell vacancy isoelectronic sequence exhibit nonmonotonic behavior as a function of nuclear charge Z. This behavior is explained in terms of an accidental degeneracy, an avoided crossing of two nearly degenerate spin-orbit coupled levels. The results also demonstrate the importance of including both electron-electron correlation and spin-orbit effects even at low Z