Analytical evaluation of higher-order binding corrections to the Lamb shift

A method of calculating the one-loop self-energy contribution to the Lamb shift is presented. The technique relies on the division into the low- and the high-energy parts. The low-energy part is calculated using the multipole expansion and the high-energy part is calculated by expanding the Dirac Coulomb propagator in powers of the Coulomb field. This method is a generalization of the original Bethe derivation of the leading-order contribution.