One-loop electron self-energy with accelerated partial-wave expansion in the Coulomb gauge

Numerical calculations of the electron self-energy without any expansion in the binding nuclear field are required in order to match the rapidly advancing precision of experimental spectroscopy. For the lightest elements, particularly hydrogen, these computations are complicated by large numerical cancelations and the slow convergence of the partial-wave expansion. Methods with accelerated convergence of the partial-wave expansion have been recently put forward [V. A. Yerokhin, K. Pachucki, and V. M. Shabaev, ; J. Sapirstein and K. T. Cheng, ]. In our work we extend the accelerated-convergence methods to the previously hardly accessible region of nuclear charges Z<5 and higher excited states. Published by the American Physical Society 2025