Faraday-cage screening reveals intrinsic aspects of the van der Waals attraction

TL;DR

This paper investigates how graphene screening affects van der Waals forces between silica surfaces, combining theory and first-principles calculations to deepen understanding and explore practical implications.

Contribution

It introduces a comprehensive analysis of vdW screening effects using advanced dispersion models and compares traditional and many-body approaches within a unified framework.

Findings

MBD screening scales as 1.25 de/d for silica bilayers

Screening effects can lead to antiscreening at certain separations

Results suggest need for improved density functional methods

Abstract

General properties of the recently observed screening of the van der Waals (vdW) attraction between a silica substrate and silica tip by insertion of graphene are predicted using basic theory and first-principles calculations. Results are then focused on possible practical applications, as well as an understanding of the nature of vdW attraction, considering recent discoveries showing it competing against covalent and ionic bonding. The traditional view of the vdW attraction as arising from pairwise-additive London dispersion forces is considered using Grimme's "D3" method, comparing results to those from Tkatchenko's more general many-body dispersion (MBD) approach, all interpreted in terms of Dobson's general dispersion framework. Encompassing the experimental results, MBD screening of the vdW force between two silica bilayers is shown to scale up to medium separations as 1.25 de/d, where d is the bilayer separation and de its equilibrium value, depicting antiscreening approaching and inside de. Means of unifying this correlation effect with those included in modern density functionals are urgently required.