Journal of Physics B: Atomic and Molecular Physics
The calculation of two-electron QED energy shifts in helium-like ions is discussed in order to correct a number of errors and misunderstandings which have appeared in the literature. New results are presented for the terms involving (r12-3) in the ground and low-lying excited states for ions up to Z=10. A detailed comparison is made with the high-precision measurement by Martin (1984) and a calculation by Hata (1984) for the 1s2p 1P1-1s2p 3P1 transition of helium.
Drake, Gordon W. F. and Makowski, A. J.. (1985). Two-electron QED corrections in helium-like ions. Journal of Physics B: Atomic and Molecular Physics, 18 (4), L103-L106.