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Communication: Ionization potentials in the limit of large atomic number
Lucian A Constantin1, John C Snyder, John P Perdew
1Department of Chemistry, University of California, Irvine, California 92697-2025, USA. lconstan@tulane.edu
The Journal of Chemical Physics
|January 5, 2011
Summary
This study shows that the ionization potential of atoms increases across a periodic table row, even for heavy elements. Local density approximation in Kohn-Sham density functional theory becomes more accurate for these extreme conditions.
Area of Science:
- Atomic Physics
- Quantum Chemistry
- Computational Materials Science
Background:
- Understanding atomic and ionic properties is crucial in chemistry and physics.
- Extrapolating electronic structure calculations to high electron counts presents significant challenges.
Purpose of the Study:
- To investigate the behavior of ionization potentials for heavy atoms and ions.
- To evaluate the accuracy of Kohn-Sham density functional theory (KS-DFT) approximations in the high-Z limit.
Main Methods:
- Extrapolation of nonrelativistic atomic and ionic energies using Kohn-Sham density functional theory.
- Analysis of the local density approximation (LDA) for exchange contributions.
- Comparison with Extended Thomas-Fermi (ETF) theory.
Main Results:
- Ionization potential remains finite and increases across a row of the periodic table as nuclear charge (Z) approaches infinity.
- The local density approximation for exchange becomes increasingly accurate, approaching exactness.
- Extended Thomas-Fermi theory accurately predicts the shell-averaged ionization potential and density change.
Conclusions:
- KS-DFT with LDA provides a robust framework for studying heavy elements.
- The behavior of ionization potentials at high Z has implications for understanding chemical trends and atomic properties.
- ETF theory offers a valuable simplified model for these systems.
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