Diao Zhao Yu, Hao Ce, Wang Ze Xin, Dong Chen Chu, Pang Xue Hui
Department of Chemistry, Shandong Normal University, Jinan 250014, China.
J Phys Chem B. 2005 Jun 30;109(25):12467-73. doi: 10.1021/jp0503258.
The adsorption, vibration, and diffusion of O atoms on Rh(100), Rh(111), Rh(110), and Rh(711) surfaces were studied using the 5-parameter Morse potential (5-MP) of interaction between an adatom and a metal surface cluster. Our theoretical calculations provide information about adsorption sites, adsorption geometry, binding energy, and eigenvibration. Our results agreed very well with experimental results. Four major results follow. First, the theoretical calculation showed that on the Rh(100) surface the 4-fold hollow site is the only adsorption site. Second, on the O-Rh(111) system, the 3-fold hollow site is the stable adsorption site. Third, on the Rh(110) surface at low coverage, the O atom is adsorbed preferably on the pseudo-3-fold site, while with increasing coverage, the O atom is adsorbed not only on the pseudo-3-fold site but also on the long bridge site. Last, as for the Rh(711) stepped surface, the 3-fold site on the (111) step is metastable, whereas the 4-fold sites on the (100) terrace are stable, which enables the O atoms to diffuse easily from the 3-fold to the 4-fold site at low coverage. Therefore, the O atoms are adsorbed preferrably on the stable 4-fold sites of the (100) terrace and then later as coverage increases on the metastable 3-fold site of the (110) step.
利用吸附原子与金属表面簇之间相互作用的五参数莫尔斯势（5-MP），研究了O原子在Rh(100)、Rh(111)、Rh(110)和Rh(711)表面上的吸附、振动和扩散。我们的理论计算提供了有关吸附位点、吸附几何结构、结合能和本征振动的信息。我们的结果与实验结果非常吻合。得出了四个主要结果。第一，理论计算表明，在Rh(100)表面，四重中空位点是唯一的吸附位点。第二，在O-Rh(111)体系中，三重中空位点是稳定的吸附位点。第三，在低覆盖度下的Rh(110)表面，O原子优先吸附在准三重位点上，而随着覆盖度的增加，O原子不仅吸附在准三重位点上，还吸附在长桥位点上。最后，对于Rh(711)阶梯表面，(111)台阶上的三重位点是亚稳态的，而(100)平台上的四重位点是稳定的，这使得O原子在低覆盖度下能够容易地从三重位点扩散到四重位点。因此，O原子优先吸附在(100)平台的稳定四重位点上，随后随着覆盖度的增加吸附在(110)台阶的亚稳态三重位点上。
