Research Article

Wavelike charge density fluctuations and van der Waals interactions at the nanoscale

Science  11 Mar 2016:
Vol. 351, Issue 6278, pp. 1171-1176
DOI: 10.1126/science.aae0509

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Describing dispersion forces

Dispersion or van der Waals interactions are attractive forces that arise from induced dipoles. They are not seen just in atoms and molecules but also in larger nanostructures and even macroscopic objects. Ambrosetti et al. created a qualitatively correct description of van der Waals interactions between polarizable nanostructures over a wide range of finite distances. This required delocalized electrons that have wavelike electron density fluctuations, unlike the more common approaches with dipoles fixed on atoms. Furthermore, the authors observed an enhancement in the nonlocality of the charge density response on the scale of 10 to 20 nm.

Science, this issue p. 1171

Abstract

Recent experiments on noncovalent interactions at the nanoscale have challenged the basic assumptions of commonly used particle- or fragment-based models for describing van der Waals (vdW) or dispersion forces. We demonstrate that a qualitatively correct description of the vdW interactions between polarizable nanostructures over a wide range of finite distances can only be attained by accounting for the wavelike nature of charge density fluctuations. By considering a diverse set of materials and biological systems with markedly different dimensionalities, topologies, and polarizabilities, we find a visible enhancement in the nonlocality of the charge density response in the range of 10 to 20 nanometers. These collective wavelike fluctuations are responsible for the emergence of nontrivial modifications of the power laws that govern noncovalent interactions at the nanoscale.

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