Pd and Ag dimers and tetramers adsorbed at the MgO(001) surface:: a density functional study

被引:74
作者
Ferrari, AM
Xiao, CY
Neyman, KM
Pacchioni, G
Rösch, N
机构
[1] Univ Milan, Dipartimento Sci Mat, Ist Nazl Fis Mat, I-20125 Milan, Italy
[2] Tech Univ Munich, Inst Theoret & Phys Chem, D-85747 Garching, Germany
关键词
D O I
10.1039/a904813h
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We have studied computationally the adsorption properties of small Ag and Pd clusters deposited on the MgO(001) surface. The calculations were carried out employing a gradient-corrected density functional approach; the oxide surface was represented by model clusters embedded in a large array of point charges. Supported Ag and Pd dimers and tetramers were investigated in order to identify the preferred adsorption sites and the modifications induced in the cluster by the interaction with the substrate. All metal clusters adsorb in proximity of oxygen centers. An adsorption mode with the molecular axis parallel to the surface is the most stable one for Pd-2 while Ag-2 prefers an upright adsorption mode. Various isomer structures of the supported metal tetramers have been considered. In general, the most stable gas phase structure is also the preferred one upon adsorption. This suggests that the metal-metal bonding prevails over the metal-MgO interaction.
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页码:4655 / 4661
页数:7
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