A computational study of the adsorption of Pyridine on Cu, Ag, Au (111) surfaces assessing the role of the van der Waals' interactions*

We study the adsorption of pyridine (C₅H₅N) on Cu, Ag, and Au(111) surfaces using van der Waals (vdW) inclusive density functional theory (vdW-DF). For this study, five difference functionals from the vdW-DF family were used. We explore a variety of adsorption sites with the molecule’s plane both parallel and perpendicular to the surface. We find pyridine prefers to adsorb perpendicular to the surface. Including the vdW interactions tends to enhance the overall adsorption energy of the pyridine molecule. We present along with the adsorption energy, various geometric properties of the substrate/adsorbate system such as adsorption height, tilt angle of the molecule, and buckling of the first layer of the substrate. We then delve into the electronic properties of the substrate/adsorbate system such as change in the surface’s work function, charge transfer, and change in the partial d-band of the atoms that compose the first layer of the substrate upon the adsorption of pyridine. Overall we find pyridine exhibits very similar adsorption characteristics on these three metallic surfaces. We also assess the performance of the five vdW inclusive functionals studied.