Second-order self-energy–vacuum-polarization contributions to the Lamb shift in highly charged few-electron ions

Proceeding towards the evaluation of the complete set of radiative corrections of order ${\mathrm{\alpha }}^2$ to the energy levels of hydrogenlike systems, the second-order self-energy–vacuum-polarization contribution to the Lamb shift of bound electrons is derived and calculated. We focus on the Uehling part of the vacuum-polarization insertion in the effective photon interaction. Additional energy corrections of order ${\mathrm{\alpha }}^2$ are also calculated. We present a brief summary of various energy contributions for K- and L-shell electrons in hydrogenlike and lithiumlike high-Z ions. © 1996 The American Physical Society.