QED calculation of the ground-state energy of berylliumlike ions

TL;DR

This paper presents highly accurate ab initio QED calculations of the ground-state energies of berylliumlike ions across a wide range of nuclear charges, improving upon previous results by including higher-order effects and advanced correlation methods.

Contribution

It introduces a comprehensive QED calculation framework combining perturbation theory and configuration-interaction methods for berylliumlike ions, with improved accuracy over prior work.

Findings

Accurate ground-state energies for Z=18-96 ions obtained.

Enhanced precision in ionization potentials compared to previous studies.

Inclusion of nuclear recoil and polarization effects.

Abstract

Ab initio QED calculations of the ground-state binding energies of berylliumlike ions are performed for the wide range of the nuclear charge number: Z=18-96. The calculations are carried out in the framework of the extended Furry picture starting with three different types of the screening potential. The rigorous QED calculations up to the second order of the perturbation theory are combined with the third- and higher-order electron-correlation contributions obtained within the Breit approximation by the use of the large-scale configuration-interaction Dirac-Fock-Sturm method. The effects of nuclear recoil and nuclear polarization are taken into account. The ionization potentials are obtained by subtracting the binding energies of the corresponding lithiumlike ions. In comparison with the previous calculations the accuracy of the binding energies and the ionization potentials is significantly improved.