Salient Signature of van der Waals Interactions

Abstract

van der Waals interactions govern the physics of a plethora of molecular structures. It is well known that the leading term in the distance-based London expansion of the van der Waals energy for atomic and molecular dimers decays as $1/R^6$, where $R$ is the dimer distance. Using perturbation theory, we find the leading term in the distance-based expansion of the intracule pair density at the interatomic distance. Our results unveil a universal $1/R^3$ decay, which is less prone to numerical errors than the $1/R^6$ dependency, and it is confirmed numerically in H${}_2$ and He${}_2$ molecules. This \textit{signature} of van der Waals interactions can be directly used in the construction of approximate pair density and energy functionals including vdW corrections.

4 pages, 3 figures

References in corpus (2)

• van der Waals forces in density functional theory: The vdW-DF method
• Interpretation of van der Waals density functionals

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