Improved QED correction model for the GRASP2018 package

TL;DR

The paper addresses improving QED corrections in atomic structure calculations by integrating the Flambaum–Ginges radiative potential into the GRASP2018 rci module. It provides updated fitting prefactors for $A(Z,n,l)$ and $B(Z,n,κ)$ across a broad $Z$ range, includes finite-nucleus-size corrections, and adds the Wichmann–Kroll vacuum-polarization term. Benchmarking against H-like, He-like, and F-like systems shows that the TW results reproduce reference values with higher fidelity than the original GO model, especially for high-$Z$ elements. The work enables on-the-fly QED corrections within Grasp2018 via the rci-q tool and provides installation and usage guidance, facilitating more accurate heavy-atom QED effects in routine calculations.

Abstract

The Rci-Q package is an extension to the GRASP2018 suite, improving the model of estimating the quantum-electrodynamics (QED) corrections to the energy levels. The Flambaum-Ginges radiative potential method is used to estimate the leading self-energy correction to electron energy in many electron atoms. The new fitting prefactors to parameterize radiative potential are presented. The correction to self-energy originating from finite nucleus size is included. The Wichmann-Kroll part of the vacuum polarization potential is also implemented.