Intrinsic Metal Size Effect on Adsorption of Organic Molecules on Platinum

Di-σ adsorbed ethene, bridge(30) adsorbed benzene (with four di-σ-type and two π-type interactions), and η1 and η2 adsorbed acetone on nanosized platinum clusters consisting of 19 to 38 Pt atoms were studied theoretically by density functional theory (DFT) calculations with general gradient approximation (GGA) utilizing plane wave and local basis sets. The cluster results were compared to plane wave calculations employed with periodic boundary conditions. It was found that the geometries obtained with different methods are very similar but the adsorption energy depends prominently on the cluster size. Adsorption was strongest on the 22- and 26-atom clusters and weakest on the 35- and 38-ato…