Va. Yerokhin et al., Rigorous quantum electrodynamics treatment of electron correlations in high-Z ions: beyond the Breit and effective-potential approximations, PHIL MAG B, 81(10), 2001, pp. 1547-1555
We discuss the present status of quantum electrodynamics (QED) investigatio
ns of electron correlations in second order in a for heavy few-electron ato
ms. A complete evaluation of all two-electron QED contributions of order al
pha (2) is presented for the 2p(1/2)-2s transition in high-Z Li-like ions.
In particular, the two-photon exchange correction beyond the Breit approxim
ation is calculated for highly charged ions with Z > 50. The total theoreti
cal value of 280.44(9)(20)eV is found for the 2p(1/2)-2s transition energy
in Li-like U.