# Chemical accuracy for the van der Waals density functional

## TL;DR

This paper demonstrates that the accuracy of the van der Waals density functional (vdW-DF) can be significantly improved for dispersion and hydrogen-bonded systems by selecting appropriate exchange functionals, achieving near chemical accuracy.

## Contribution

The study identifies and tests new exchange functionals that enhance the vdW-DF's accuracy for weakly interacting systems and adsorption phenomena.

## Key findings

- vdW-DF with optimized exchange functionals achieves chemical accuracy on S22 benchmark set.
- Improved predictions for water clusters and water adsorption on salt.
- Significant performance enhancement over previous vdW-DF implementations.

## Abstract

The non-local van der Waals density functional (vdW-DF) of Dion et al. [Phys. Rev. Lett. 92, 246401 (2004)] is a very promising scheme for the efficient treatment of dispersion bonded systems. We show here that the accuracy of vdW-DF can be dramatically improved both for dispersion and hydrogen bonded complexes through the judicious selection of its underlying exchange functional. New and published exchange functionals are identified that deliver much better than chemical accuracy from vdW-DF for the S22 benchmark set of weakly interacting dimers and for water clusters. Improved performance for the adsorption of water on salt is also obtained.