Carbon-rich C9Sin (n = 1–5) clusters from ab initio calculations

The carbon-rich structures of C9Sin (n = 1–5) clusters were studied by first-principles density functional calculations using the B3LYP hybrid exchange–correlation energy functional and 6-311++G(2df) basis set. By systematic investigation of the structures and energies, we found that in the structures of the carbon-rich clusters C9Sin (n = 1–5), the C atoms were found to form linear (n = 2), or single-ring (n = 1 and 3) or double-rings (n = 4 and 5) while the Si atoms prefer to attach to the carbon rings in the form of C2Si units. Based on the lowest-energy structures obtained from our calculations, the properties of the clusters such as binding energy, second difference in energy, HOMO–LUMO gap, adiabatic ionization potential (AIP), adiabatic electron affinity (AEA), vibrational frequency, bond orders and NBO charge transfer have been calculated and analyzed.