MANY-BODY CALCULATION OF THE 2P(1/2,3/2)-2S(1/2) TRANSITION ENERGIES IN LI-LIKE U-238

We present a relativistic many-body calculation of the 2s1/2 and 2p1/2,3/2 ionization energies in Li-like U238, based on the coupled-cluster singles and doubles approximation with the inclusion of the unretarded Breit interaction, using Dirac-Fock-Breit orbitals. A detailed comparison is made with a similar calculation using ordinary Dirac-Fock orbitals. The calculation yields the transition energies, and by comparison with the recently published experimental values we find the value for the remaining quantum-electrodynamical correction, which is compared with recent Lamb-shift calculations. The importance of an accurate nuclear model for evaluating the nuclear-size effect is also discussed. © 1994 The American Physical Society.