Finite size dependent dispersion potentials between atoms and ions dissolved in water

TL;DR

This paper develops a non-expanded theory for dispersion potentials between atoms and ions in water, highlighting the significant impact of finite-size effects and retardation, especially in excited states and at small separations.

Contribution

It introduces a comprehensive non-expanded approach that incorporates finite-size, retardation, and medium effects into dispersion interactions in aqueous environments.

Findings

Finite-size corrections can alter dispersion interactions by several orders of magnitude.

Retardation effects dominate interactions for excited helium atom pairs at small separations.

Finite-size effects are crucial when particles are close, significantly affecting dispersion potentials.

Abstract

A non-expanded theory is used for dispersion potentials between atoms and ions dissolved in a medium. The first-order dispersion interaction between two atoms in an excited state must account for the fact that the two atoms are coupled via the electromagnetic field and must include effects from background media, retardation and finite size. We show that finite-size corrections when two particles are close change the dispersion interactions in water by several orders of magnitude. We consider as four illustrative examples helium atoms, krypton atoms, phosphate ions, and iodide ions. We demonstrate that, due to large cancellation effects, retardation dominates the interaction for helium atom pairs in an isotropic excited state down to the very small atom-atom separations where finite-size corrections are also important