High precision atomic theory for Li and Be+: QED shifts and isotope shifts.

TLDR: High-precision results are presented for calculations of the nonrelativistic energies, relativistic corrections, and quantum electrodynamic corrections for the 2 2S, 2 2P, and 3 2S states of Li and Be+, using nonrel ativistic wave functions expressed in Hylleraas coordinates.

Abstract: High-precision results are presented for calculations of the nonrelativistic energies, relativistic corrections, and quantum electrodynamic corrections for the $2\text{ }^{2}S$, $2\text{ }^{2}P$, and $3\text{ }^{2}S$ states of Li and ${\mathrm{Be}}^{+}$, using nonrelativistic wave functions expressed in Hylleraas coordinates. Bethe logarithms are obtained for the states of ${\mathrm{Be}}^{+}$. Finite mass corrections are calculated with sufficient accuracy to extract the nuclear charge radius from measurements of the isotope shift for the $2\text{ }^{2}S\ensuremath{-}2\text{ }^{2}P$ and $2\text{ }^{2}S\ensuremath{-}3\text{ }^{2}S$ transitions. The calculated ionization potential for ${\mathrm{Be}}^{+}$ is $146\text{ }882.923\ifmmode\pm\else\textpm\fi{}0.005\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$.