A Density Functional Theory Study of the Adsorption of Thiophene on Transition Metal Surfaces

Using density functional theory we study the adsorption of thiophene (C₄H₄S) over a wide variety of transition metal surfaces including V, Cr, Ta, W, Mo, Nb, Co, and Al(100). To account for long range dispersion we utilize the van der Waals (vdW) inclusive optB88-vdW functional. We explore several adsorption sites with the plane of the molecule either parallel or perpendicular to the surface. We find that on all of the surfaces thiophene prefers to bond in a flat configuration. Along with the equilibrium adsorption sites, we present a variety of other properties of the substrate/adsorbate system including adsorption energy, adsorption height, C-S bond lengths, and charge transfer to the molecule. Using the previously mentioned geometric and electronic data we find the thiophene/substrate interaction increases moving from right to left on the periodic table. Focusing specifically on charge transfer to the thiophene molecule, we find a strong correlation between the charge transfer to thiophene’s S atom and the thiophene/substrate interaction, which we build into a descriptor for the surfaces’ reactivity.