Quantum Electrodynamical Corrections to Energy Levels of Diatomic Quasimolecules

We elaborate an ab initio approach for the evaluation of the one-loop quantum electrodynamical corrections to energy levels of diatomic quasimolecules. The approach accounts for the interaction between an electron and two nuclei in all orders in $Z\alpha$ and can be applied for a wide range of internuclear distances, up to $R\approx 1000\mathrm{fm}$. Based on the developed theory, detailed calculations are performed for the self-energy and vacuum-polarization corrections to the energy of the $1{\sigma }_g$ ground state of the ${\mathrm{U}}^{92+}–{\mathrm{U}}^{91+}$ dimer that can be produced in slow ion-ion collisions. The calculations predict the remarkable energy shift that arises due to the nonspherical contributions to the electron-nuclei potential taken beyond the standard monopole approximation.

Figure 1

Feynman diagrams representing (a) self-energy and (b) vacuum-polarization corrections to the energy levels. We display also the decomposition of self-energy diagram into zero-, first-, and many-potential terms.