Towards superior van der Waals density functionals for molecular crystals

TL;DR

This paper develops a new computational scheme combining van der Waals density functionals to improve the accuracy of molecular crystal predictions within density functional theory.

Contribution

It introduces a combined vdW functional approach that enhances the description of molecular crystals and sparse materials in density functional calculations.

Findings

Improved prediction accuracy for molecular crystal structures.

Enhanced theoretical description of van der Waals interactions.

Validated approach on X23 molecular crystal dataset.

Abstract

Ubiquitous van der Waals (vdW) interactions play a subtle yet crucial role in determining the precise atomic arrangements in solids, particularly in molecular crystals where these weak forces are the primary link between constituent building blocks. Within density functional (DF) theory, the most natural approach for addressing vdW forces is the use of vdW-inclusive density functionals. Through a detailed analysis of the underlying formalism, we have developed a computational scheme that combines vdW functionals of type DF1 and DF2 and serves as a well optimizable tool to improve the theoretical description and prediction of molecular crystals and other sparse materials. The proof of principle is demonstrated by our consideration of the molecular crystals from the X23 dataset.