Theoretical investigation on the structures of silicon and carbon hetero clusters

Structures and energies of Si_mC_n clusters (m = 2 - 6, n = 1 - m) have been investigated systematically at MP2/6-311G(d) level of theory. Several stable structures of Si₆C_n are predicted for the first time. All the structures show that carbon atoms prefer forming kernels at the center of framework, surrounded by silicon atoms with small coordination number. The strong C{single bond}C bond favored over Si{single bond}C bond determines the structure of Si_mC_n clusters. The binding energies show that the systems with the ratio of Si:C=1:1 have the larger stability compared to the Si-rich hetero systems.