English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

I revisit the problem of the interaction between two dissimilar atoms withone atom in an excited state, recently addressed by the authors of Refs.[1-3],and for which precedent approaches have given conflicting results. In the firstplace, I discuss to what extent Refs.[1], [2] and [3] provide equivalentresults. I show that the phase-shift rate of the two-atom wave functioncomputed in Ref.[1], the van der Waals potential of the excited atom in Ref.[2]and the level shift of the excited atom in Ref.[3] possess equivalentexpressions in the quasistationary approximation. In addition, I show that thelevel shift of the ground state atom computed in Ref.[3] is equivalent to itsvan der Waals potential. A diagrammatic representation of all those quantitiesis provided. The equivalences among them are however not generic. Inparticular, it is found that for the case of the interaction between twoidentical atoms excited, the phase-shift rate and the van der Waals potentialsdiffer. Concerning the conflicting results of previous approaches in regards tothe spatial oscillation of the interactions, I conclude in agreement withRefs.[1,3] that they refer to different physical quantities. The impacts offree-space dissipation and finite excitation rates on the dynamics of thepotentials are analyzed. In contrast to Ref.[3], the oscillatory versusmonotonic spatial forms of the potentials of each atom are found not to berelated to the reversible versus irreversible nature of the excitation transferinvolved.

Two-atom interaction energies with one atom in an excited state: van der Waals potentials vs. level shifts