Attractive and repulsive terms in multi-filament dispersion interactions

TL;DR

This paper investigates the complex van der Waals interactions among filamentary objects like nanotubes and DNA, revealing alternating attractive and repulsive multi-object forces and emphasizing the need for non-perturbative methods for accurate predictions.

Contribution

It provides the first detailed analysis of multi-filament vdW interactions, showing sign alternation with object number and offering new insights into screening effects.

Findings

vdW energy contributions alternate in sign with increasing object number

Detailed analysis of a 4-cylinder vdW model confirms theoretical predictions

Non-perturbative calculations are necessary for accurate interaction predictions

Abstract

Filamentary objects such as nano-wires, nanotubes and DNA are of current interest in physics, nanoscience, chemistry, biology and medicine. They can interact via strong, exceptionally long-ranged many-object van der Waals (vdW, dispersion) forces, causing them to cluster into multi-object bundles. We analyse their vdW interactions perturbatively, predicting $N$-object vdW energy contributions that alternate in sign with increasing $N$. Our findings are confirmed here via the first detailed analysis of a 4-cylinder vdW model. We also provide novel insights permitting these tendencies to be understood simply in terms of electronic screening and anti-screening. Our results suggest that a non-perturbative calculation will be required for reliable prediction of dispersion interactions in these ubiquitous systems.