Model potential for silicon clusters and surfaces

A previously developed model potential for Si, which was successful in simulating structural and dynamical properties of small Si clusters, was further improved with the introduction of a four-body term that includes second-neighbor interactions. The model offers a good simulation of cluster properties and produces satisfactory results concerning the (111) and (100) surface reconstruction. Moreover, a better fitting of the local-density-approximation results concerning high-energy bulk structures is obtained, while the elastic properties of the Si crystal are well described. These results show that the introduction of this four-body term, which describes the dihedral angle dependence in Si-Si interactions, is crucial for developing a universal model that correctly reproduces structural and dynamical properties of bulk, surface, and cluster phases of silicon.