Growth pattern of doubly metal doped silicon clusters M2Sin with M2 = Mo2, Nb2, Ta2, W2, NbMo, TaW and n = 11–18. Formation of fused cages M2Si18

Abstract

Geometries of doubly transition metal doped silicon clusters M2Sin, M2 = Mo2, Nb2, Ta2, W2, NbMo, TaW were determined by DFT computations. Geometries of M2Sin in the range from 11 to 18 Si atoms change from a tubular shape to a cage and then a fused cage. The M2Si18 sizes present us with a novel structural motif, the fused cage, for silicon clusters. Such fused cages arise from a fusion of both MSi10 and MSi12 prisms followed by addition of two Si atoms. Formation and filling of electron shells contribute to the high thermodynamic stability of M2Si18 fused clusters.