Adsorption of Large Hydrocarbons on Coinage Metals: A van der Waals Density Functional Study

The adsorption of organic molecules onto the close-packed facets of coinage metals is studied, and how accurately adsorption heights can be described by using recent advances of the van der Waals density functional (vdWDF), with optPBE/vdWDF, optB86b/vdWDF, vdWDF2, and rev/vdWDF2 functionals is illustrated. The adsorption of two prototypical aromatic hydrocarbons is investigated, and the calculated adsorption heights are compared to experimental literature values from normal incident X-ray standing wave absorption and a state-of-the-art semi-empirical method. It is shown that both the optB86b/vdWDF and rev/vdWDF2 functionals describe adsorption heights with an accuracy of 0.1 angstrom, compared to experimental values, and are concluded as reliable methods of choice for related systems.