Relaxation and final-state channel mixing in the Auger effect

The conventional theory of the Auger effect, based on Wentzel's ansatz (1927), is generalised to incorporate relaxation and final-state channel mixing. An application to neon KLL Auger rates in LS coupling is made. The bound-state orbitals are generated by alternative self-consistent-field methods and the continuum orbital is solved in the field of the doubly ionised residual ion including full exchange. In accordance with Kelly's many-body-perturbation-theory calculation (1975), it is found that the mixing between the final 2 S channels affects the various partial rates by 10 to 40%. The effect of the non-orthogonal overlap elements is found to be of importance for the KL 1 L 1 1 S and KL 1 L 2,3 3 P transitions. Since the Slater integrals involved are shown to be sensitive to the relevant orbitals, the importance of incorporating correlation effects in a systematic fashion is stressed.