Energetically Competitive Growth Patterns of Silicon Clusters: Quasi-one-dimensional Clusters versus Diamond-like Clusters

Silicon clusters with a diamond-like core and energetically competitive non-diamond clusters were comparatively studied using the nonconventional tight-binding molecular dynamics simulation method. Non-diamond clusters were constructed according to a quasi-onedimensional pentagon-based regular growth pattern. A non-trivial competition between surface and core reconstructions in the clusters, in order to reach energetically favorable atomic arrangements, was observed. This prevents unlimited growth via the one-dimensional pattern. Starting from Si43, there was substantial deviation from the stacked pentagon motif, and for Si61 one end of these clusters became almost two-dimensional. The structure of clusters with a diamond-like core was subject to substantial reconstruction for the cluster sizes considered (≤ 71 atoms). By extrapolating the present results, a lower bound for the transition from non-diamond structure to diamond-like structure is estimated to be 115 atoms. PACS numbers: 71.15.Nc, 61.46.+w, 73.22.-f