Molecular Adsorption on Metal Surfaces with a van der Waals Density Functional

TL;DR

This paper demonstrates that incorporating van der Waals interactions in density functional theory significantly improves the accuracy of modeling molecular adsorption on noble metal surfaces, aligning well with experimental data.

Contribution

It introduces the use of a non-local van der Waals density functional (vdW-DF) for better prediction of adsorption energies and geometries on metal surfaces, providing a practical benchmark.

Findings

vdW-DF enhances adsorption energy predictions

Geometry of molecules is significantly affected by dispersion interactions

vdW-DF outperforms other dispersion-corrected DFT methods

Abstract

The adsorption of 1,4-benzenediamine (BDA) on the Au(111) surface and azobenzene on the Ag(111) surface is investigated using density functional theory (DFT) with a non-local density functional (vdW-DF) and a semi-local Perdew-Burke-Ernzerhof (PBE) functional. For BDA on Au(111), the inclusion of London dispersion interactions not only dramatically enhances the molecule-substrate binding, resulting in adsorption energies consistent with experimental results, but also significantly alters the BDA binding geometry. For azobenzene on Ag(111), the vdW-DF produces superior adsorption energies compared to those obtained with other dispersion corrected DFT approaches. These results provide evidence for the applicability of the vdW-DF method and serves as a practical benchmark for the investigation of molecules adsorbed on noble metal surfaces.