Ionization energies along beryllium isoelectronic sequence

TL;DR

This paper provides highly accurate ionization energies for berylliumlike ions across a wide range of nuclear charges by combining advanced quantum electrodynamics calculations with electron-correlation effects.

Contribution

It introduces a comprehensive method that merges ab initio QED with electron-correlation contributions within the Breit approximation for the first time.

Findings

Significant improvement in ionization energy accuracy.

Extended calculations up to Z=96.

Inclusion of nuclear recoil and polarization effects.

Abstract

Ionization energies for the ground state of berylliumlike ions with nuclear charge numbers in the range Z=16-96 are rigorously evaluated. The calculations merge the ab initio QED treatment in the first and second orders of the perturbation theory in the fine-structure constant $\alpha$ with the third- and higher-order electron-correlation contributions evaluated within the Breit approximation. The nuclear recoil and nuclear polarization effects are taken into account. The accuracy of the ionization energies obtained has been significantly improved in comparison with previous calculations.