Table of Contents
ISRN Inorganic Chemistry
Volume 2013 (2013), Article ID 689040, 10 pages
Research Article

Relativistic Corrections for Calculating Ionization Energies of One- to Five-Electron Isoelectronic Atomic Ions

School of Biological and Chemical Sciences, Birkbeck College, University of London, Malet Street, London WC1E 7HX, UK

Received 20 August 2012; Accepted 1 October 2012

Academic Editors: A. M. Fonseca, A. Karadag, and Z. Wu

Copyright © 2013 Peter F. Lang and Barry C. Smith. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We have previously proposed a simple empirical equation to reproduce the literature values of the ionization energies of one-electron to four-electron atomic ions with very good agreement. However, we used a potential energy approach in our equation, which has no theoretical basis. This paper discusses an alternative kinetic energy expression for one to five electrons with simple corrections for relativistic and Lamb shift effects and for two- to-five electron ions additional effects including electron relaxation and residual interactions. For calculated values of one-electron (hydrogen-like) and two electron (helium like) atomic ions, the difference with the literature values is typically 0.001% or less. Agreement with the literature values for three-, four-, and five-electron ions is 99% or better. First electron affinities calculated by our expression also agree fairly well with generally recommended values. These results show that there is strong evidence that our methodology can be developed to reliably predict, with fairly good accuracy, ionization energies of multielectron atomic ions that have not been measured.