Calculation of a divergence-free lamb shift

A divergence-free theory of the Lamb shift is presented, and calculations are carried out for hydrogen-like ions. The theory uses two Lorentz-invariant equations of motion, one for the electron in the presence of the photon, which is Dirac's four-space time-dependent equation, and the other for the photon in the presence of the electron. The electronphoton interaction is calculated from the Dirac current. The distribution of photon frequencies is bounded by the distribution of electron frequencies intrinsic to the Dirac current, thereby guaranteeing a divergence-free result for the Lamb shift. (C) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011