Physisorption of benzene on a tin dioxide surface: Van der Waals interaction

An adsorption study of the benzene molecule on SnO ₂ (110) surfaces with the density functional theory is extended to include the van der Waals interaction. We compare adsorption onto two model surfaces of SnO ₂, oxygen rich (stoichiometric) and oxygen poor (reduced), considered as limiting cases of varying oxygen abundance. With the chosen van der Waals approach it is found that on the stoichiometric surface, where binding has both a covalent nature and an ionic nature, with the addition of the van der Waals interaction the adsorption energy becomes somewhat stronger. However, on the reduced surface, where binding was earlier predicted to be more physisorptionlike by using a standard generalized gradient approximation (GGA) approach, the van der Waals interaction increases the adsorption energy by a larger factor. Furthermore, three different local-density approximation and GGA functionals are compared, as corrected with the van der Waals scheme. It is found that the correction brings those three to reasonably similar descriptions of adsorption on both surfaces. © 2012 American Physical Society.