Interatomic distance in diatomic molecules

[Malamala]

Hello! I know this question is quite random, but I wasn't sure how else to search for this. Assume we have a diatomic molecule with one large and one small nucleus, for example BaF, such that the electron (assume there is just one electron outside the open shell) is localized around the massive nucleus. Is there anything we can learn from the electron density at the massive nucleus as a function of the internuclear distance i.e. $\rho_e^{Ba}(R)$? Are there any new physics models (or even SM observables) that can be constrained by measuring this dependence? Thank you!

 

[phyzguy]

Atomic physics is well understood. At the distances and energies involved in diatomic molecules, quantum electrodynamics is extremely accurate, and any discrepancies between theory and experiment would be unmeasurably small. If you are looking to get insight on new physics beyond the standard model, you need to go to (much) higher energies.

 

[Twigg]

If you are looking to get insight on new physics beyond the standard model, you need to go to (much)

This is not entirely true. Atomic physics experiments confirmed the values of the electron g-2 and fine structure constant that put QED on a pedestal to begin with. In recent decades, tabletop atomic physics experiments have surpassed accelerators in niche experiments, like the search for the electron's electric dipole moment. And the traditional measurements of electron g-2 or fine structure constant continue to make accelerators drool. What atomic physics systems lack in energy scale, they make up for in sensitivity.

@Malamala Need some time to think it over. It feels like it'd have to be a three-body interaction since it depends on both the internuclear distance AND the electron density at the massive nucleus.