ABSTRACT
Free atomic clusters of nanometer size normally exhibit unique properties di erent from those of individual atoms, molecules, or bulk materials [1-3]. e physicochemical properties of the clusters sometimes change dramatically with the addition or removal of one atom from a cluster-a fact that a ects the application of the nanomaterials. erefore, in recent decades, there has been lots of interest in searching, characterizing, and studying the property of nanometer-size clusters for potential applications in nanoscience and nanotechnology [4-10]. For many applications, these clusters need to be supported by solid surfaces such as in catalysts [11,12] and electronic materials. In such cases, the substrate asserts some in uence on the cluster property. Depending on how strong the interaction is, the shape and properties of the cluster can be changed [13-16]. Atomistic models frequently used for understanding the growth of surface clusters are the process of nucleation, surface di usion, growth, and coarsening. In general, clusters would grow into three-dimensional (3D) structures. For some systems, especially for metallic clusters, however, they can grow into planer shapes. e atness of the clusters either results from an intrinsic size e ect due to their electronic properties or from their interaction with the substrate. O entimes, both these factors play an equally important role.
