Relativistic, retardation, and radiative corrections in Rydberg states of lithium

We have used third-order perturbation theory to calculate the effect of the Breit-Pauli relativistic interaction on the dipole polarizability of Li+ ions of order alpha(2). Results are in good agreement with the value obtained by Johnson and Cheng [Phys. Rev. A 53, 1375 (1996)] in addition, the retardation (Casimir) corrections to singly excited (ls(2) NL) states of neutral lithium have been computed. When both of these corrections are added to the previously calculated Rydberg state energies, 1 sigma agreement is found with experiment [N. E. Rothery et nl., Phys. Rev. A 51, 2919 (1995)]. Addition of radiative (Lamb-shift) corrections produces essentially exact agreement.