The influence of dielectric properties on van der Waals/Casimir forces in solid-liquid systems

TL;DR

This paper investigates how dielectric properties influence van der Waals and Casimir forces in solid-liquid systems, highlighting the impact of dielectric data variability on force calculations and the limitations of Lifshitz theory accuracy.

Contribution

It provides a detailed analysis of the sensitivity of Lifshitz theory calculations to dielectric data quality in solid-liquid systems.

Findings

Dielectric data scatter can cause force calculation variability up to a factor of two.

Uncertainty in dielectric functions leads to up to 100% prediction error.

Lifshitz theory predictions of force transitions and scaling are affected by dielectric uncertainties.

Abstract

In this article we present calculations of van der Waals/Casimir forces, described by Lifshitz theory, for the solid-liquid-solid system using measured dielectric functions of all involved materials for the wavelength range from millimeters down to subnanometers. It is shown that even if the dielectric function is known over all relevant frequency ranges, the scatter in the dielectric data, can lead to very large scatter in the calculated van der Waals/Casimir forces. Especially when the liquid dielectric function becomes comparable in magnitude to the dielectric function of one of the interacting solids, the associated variation in the force can be up to a factor of two for plate-plate separations 5-500 nm. This corresponds to an uncertainty up to 100% in the theory prediction for a specific system. As a result accuracy testing of the Lifshitz theory under these circumstances is rather questionable. Finally we discuss predictions of Lifshitz theory regarding multiple repulsive-attractive transitions with separation distance, as well as nontrivial scaling of the van der Waals/Casimir force with distance.