Surface Energy and Electronic Structures of Ag Quasicrystal Clusters

Size-dependent surface energy associated with atomic number N, γ(N), of Ag quasicrystal clusters was investigated using density functional theory and broken-bond theory. It is found that the value of γ(N) is 0.55−0.66 eV/atom, similar to the value of their counterparts in bulk. This is due to the increase of cohesive energy Ec(N) and the decrease of surface coordinate number associated with the decreasing of N. As N decreases, the partial density of states shifts to higher binding energy, and there is electronic charge transfer from the sp band into the d band, which leads to the increase of cohesive energy.