Density-functional study of SinCn (n = 10–15) clusters

. Density-functional theory with generalized gradient approximation for the exchange-correlation potential has been used to calculate the structural and electronic properties of Si n C n ( n = 10–15) clusters. We find that the Si n C n clusters prefer cagelike structures. An extensive isomer search shows that the lowest-energy arrangements are those in which the silicon atoms and the carbon atoms form two distinct subunits. It is found that the carbon atoms favor to form fullerene-like structure due to the sp 2 -like bond. The silicon atoms are trying to cope with an unfavorable sp 2 environment, but distorted tetrahedra still show up somewhere of the cagelike structures. On the basis of the lowest-energy geometries obtained, the binding energy, HOMO–LUMO gap, Mulliken charge, ionization potential and electron affinity of the clusters have been computed and analyzed. An electronic charge transfer from the Si-populated to the C-populated regions is observed.