title: Embedded cluster density functional and second-order Møller-Plesset perturbation theory study on the adsorption of N2 on the rutile (110) surface.
abstract: The adsorption of N(2) on the rutile TiO(2) (110) surface in the limit of low coverage has been studied as a prototype example for the adsorption of non-polar molecules on strongly ionic oxide surfaces. We employed for this study an embedded cluster ansatz in combination with density functional theory and wavefunction methods. Both, clusters saturated with hydrogen atoms and electrostatically embedded clusters have been applied and methods and basis sets have been varied to test their reliability and accuracy for describing the electrostatic potential on the surface and its interaction with the non-polar N(2) molecule. Quantum clusters consisting of up to 342 atoms have been used to converge the results with respect to the cluster size. For electrostatically embedded clusters, the convergence can considerably be enhanced by optimizing the charges for the point charge embedding. On the rutile (110) surface an accurate account of the long ranging interaction of the adsorbate with the bridging oxygen atoms is important for quantitative adsorption energies of weakly bound molecules. In addition the geometric relaxation of the surface has a marked influence on the results, whereas the basis set-dependence is small. Of all methods investigated (HF, DFT/PBE, DFT/B3LYP, MP2), only MP2 and DFT/B3LYP were able to describe the adsorption of N(2) on the rutile surface properly. After including the zeropoint vibrational energy, the calculated adsorption energy is close to experimental results. The approach is thus promising for future investigations on adsorption energies and structures of non-polar molecules on ionic oxide surfaces.
authors.affiliation: Department of Theoretical Chemistry, Ruhr-Universität Bochum, D-44780 Bochum, Germany. dorothee.stodt@rub.de
authors.forename: Dorothee
authors.initials: D
authors.lastname: Stodt
authors.forename: Christof
authors.initials: C
authors.lastname: Hättig
mesh_terms: D000327:Adsorption; D009584:Nitrogen / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D011789:Quantum Theory; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D010087:Oxides; C009495:titanium dioxide; D014025:Titanium; D009584:Nitrogen