though here the many-body aspect of the problem may not be readily determined. On the other hand, the QED part of the problem may be simplified and the full many-body treatment employed. Several such “radiative potentials” have been advocated for use in many-body calculations. These include the local potentials [@pyykko; @rad_pot] and the more sophisticated non-local potential [@shabaev], all fitted to self-energy shifts in hydrogenlike ions.

There are a number of recent works where QED radiative corrections have been included into the many-body problem using one or other of these radiative potentials (e.g., [@thierfelder; @roberts; @radium; @nature]). However, there has as yet been no in-depth study of the interplay between radiative corrections and many-body effects or of the breakdown of different terms. Therefore, it is important to demonstrate the significance of different many-body effects so that they may be considered appropriately in high-precision calculations.

Derevianko [*et al.*]{} [@derev_relax] studied the effects of core relaxation on valence $s$ and $p$ level shifts of neutral Cs due to the Uehling potential in the relativistic Hartree-Fock approximation. They demonstrated how important these relaxation effects are, particularly for orbitals with orbital quantum number $l>0$. In this paper we extend the work of Derevianko [*et 