Hartree-Fock Critical Nuclear Charge in Two-Electron Atoms

Hugh G. A. Burton

doi:10.1063/5.0043105

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arXiv · 2101.02445

Hartree-Fock Critical Nuclear Charge in Two-Electron Atoms

Hugh G. A. Burton

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Abstract

Electron correlation effects play a key role in stabilising two-electron atoms near the critical nuclear charge, representing the smallest charge required to bind two electrons. However, deciphering the importance of these effects relies on fully understanding the uncorrelated Hartree-Fock description. Here, we investigate the properties of the ground state wave function in the small nuclear charge limit using various symmetry-restricted Hartree-Fock formalisms. We identify the nuclear charge where spin-symmetry breaking occurs to give an unrestricted wave function that predicts the ionisation of an electron. We also discover another critical nuclear charge where the closed-shell electron density detaches from the nucleus, and identify the importance of fractional spin errors and static correlation in this limit.

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Hugh G. A. Burton. 2021-01-07. Hartree-Fock Critical Nuclear Charge in Two-Electron Atoms. https://doi.org/10.1063/5.0043105

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