Pre-Born-Oppenheimer Dirac-Coulomb-Breit computations for two-body systems

• URL: http://arxiv.org/abs/2301.13477v2
• Date: Fri, 24 Mar 2023 22:42:45 GMT
• Title: Pre-Born-Oppenheimer Dirac-Coulomb-Breit computations for two-body systems
• Abstract summary: The Dirac--Coulomb--Breit equation is derived from the Bethe--Salpeter equation. The $alpha$ fine-structure-constant dependence of the variational energies, through fitting a function of $alphan$ and $alphantextlnalpha$ terms, shows excellent agreement with the relevant energy expressions of the (perturbative) non-relativistic QED framework.
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• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: The sixteen-component, no-pair Dirac--Coulomb--Breit equation, derived from the Bethe--Salpeter equation, is solved in a variational procedure using Gaussian-type basis functions for the example of positronium, muonium, hydrogen atom, and muonic hydrogen. The $\alpha$ fine-structure-constant dependence of the variational energies, through fitting a function of $\alpha^n$ and $\alpha^n\text{ln}\alpha$ terms, shows excellent agreement with the relevant energy expressions of the (perturbative) non-relativistic QED framework, and thereby, establishes a solid reference for the development of a computational relativistic QED approach.

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