Resolving the structure-energy dilemma at organic-inorganic interfaces: Adsorption of benzene, thiophene, and xenon over coinage metal surfaces

TL;DR

This paper introduces a new DFT+vdW-dZK method that accurately models molecule-surface interactions involving van der Waals forces, improving predictions of adsorption energies and geometries for organic molecules on coinage metal surfaces.

Contribution

The paper presents the DFT+vdW-dZK scheme, an alternative approach that enhances the accuracy of modeling physisorption of molecules on metal surfaces, outperforming existing methods.

Findings

DFT+vdW-dZK accurately predicts adsorption energies and geometries.

SCAN+vdW-dZK provides particularly good results.

Method effectively models rare-gas and organic molecule adsorption on coinage metals.

Abstract

Semilocal (SL) density functional approximations (DFAs) are widely applied but have limitations due to their inability to incorporate long-range van der Waals (vdW) interaction. Non-local functionals (vdW-DF, VV10, rVV10) or empirical methods (DFT+D, DFT+vdW, DFT+MBD) are used with SL-DFAs to account for such missing interaction. The physisorption of a molecule on the surface of the coinage metals (Cu, Ag, and Au) is a typical example of systems where vdW interaction is significant. However, it is difficult to find a general method that reasonably describes both adsorption energy and geometry of even the simple prototypes of cyclic and heterocyclic aromatic molecules like benzene (C6H6) and thiophene (C4H4S) respectively, with reasonable accuracy. In this work, we present an alternative scheme based on Zaremba-Kohn's theory, called DFT+vdW-dZK. We show that, unlike other popular methods, DFT+vdW-dZK and particularly SCAN+vdW-dZK gives an accurate description of the physisorption of a rare-gas atom (Xe) and two small albeit diverse prototype organic molecules on the (111) surfaces of the coinage metals.