Ionization potentials in the limit of large atomic number

TL;DR

This study uses large-scale density functional theory calculations to analyze ionization potentials of atoms with up to 3000 electrons, revealing finite limits and accuracy of local density approximation at large atomic numbers.

Contribution

It provides the first large-scale extrapolation of ionization potentials to the limit of infinite atomic number using non-relativistic density functional theory.

Findings

Ionization potential remains finite as Z approaches infinity.

Local density approximation becomes chemically accurate or exact in some cases.

Extended Thomas-Fermi theory matches shell-averaged ionization potential and density change.

Abstract

By extrapolating the energies of non-relativistic atoms and their ions with up to 3000 electrons within Kohn-Sham density functional theory, we find that the ionization potential remains finite and increases across a row, even as $Z\rightarrow\infty$. The local density approximation becomes chemically accurate (and possibly exact) in some cases. Extended Thomas-Fermi theory matches the shell-average of both the ionization potential and density change. Exact results are given in the limit of weak electron-electron repulsion.