Bound-electron self-energy calculations in Feynman and Coulomb gauges: Detailed analysis
Phys. Rev. A 114, 032803 – Published 2 September, 2026
DOI: https://doi.org/10.1103/y37j-k8r9
Abstract
The energy correction associated with the self-energy diagram is the leading (in magnitude) and fundamental (in significance) contribution to the Lamb shift in few-electron atoms and ions. Conventional approaches to this correction rely on partial-wave expansion, which is a major limitation on the achievable accuracy. To elucidate the issue, we perform a comprehensive comparative analysis of partial-wave-expansion convergence between the Feynman and Coulomb gauges. We also implement and discuss several techniques for improving the convergence. Both the Green's function and finite basis set are employed in the calculations.
