One- and two-electron ions are of fundamental interest for testing quantum electrodynamics and the ions U⁹⁰⁺ and U⁹¹⁺ have been produced on the Super-HILAC accelerator at Lawrence Berkeley Laboratory. The transition 1s²p³P_o-1s²s³S_l has been measured at 260 ± 7.9 eV (86.5). Indelicato used the multiconfiguration Dirac-Fock method to evaluate with a high precision thirteen contributions to the energy of this transition. His result is within the experimental error bars (88.7).

The ls, 2s and 2p energy levels of hydrogen-like uranium have been calculated by Johnson and Soff. Seven contributions to the total Lamb shift are considered and their accuracy is discussed in (85.1).