Relativistic and QED Energies in Lithium

High-precision variational results are reported for the total relativistic corrections, the anomalous magnetic moment corrections, and the electron-electron QED corrections in lithium up to orders O(α⁴mc²), O((μ/M)α⁴mc²), O(α⁵mc²), and O((μ/M)α⁵mc²) using fully correlated basis sets. Methods of estimating the dominant electron-nucleus QED term are discussed, and an extension of the Kabir-Salpeter formalism is found to yield good agreement with high-precision measurements for the ionization potential of the lithium ground state and the 1s²2s²S-1s²2p²PJ transition energies.