Electronic Structure Studies of Silicon Carbide Cationic Nanoclusters

As a continuation of our studies on the high stabilities and associated electronic structure properties of Si$_{8}$C$_{2 }$to Si$_{14}$C$_{2}$ and Si$_{20}$C$_{n }$(n=3-6) clusters,$^{1}$ we report here detailed \textit{ab initio} electronic and geometric structure studies of small $Si_m C_n^+ $(1\underline {$<$ }m, n \underline {$<$} 4) cationic clusters. The theoretical formalism used is the local density approximation (LDA) to density functional theory (DFT) and the \textit{Gaussian03} suite of programs$^{2}$ with an all electron 6-311++G** basis set has been used. Complete geometry optimizations of different possible structures have been carried out. The stability of the clusters varies with the ratio of the number of silicon to carbon atoms in the cluster. In contrast to the neutral clusters,$^{3}$ cationic clusters appear to prefer more open structures. Results will be presented for binding energies, relative energies, fragmentation energies, vibrational frequencies, and adiabatic ionization potentials$^{3}$ for the optimized clusters. Detailed comparisons with published data in the literature will also be presented. * Work supported, in part, by the Welch Foundation, Houston, Texas (Grant No. Y-1525) $^{1}$M. N. Huda and A. K. Ray, Phys. Rev. A (R) \textbf{69}, 011201 (2004); Eur. Phys. J. D \textbf{31}, 63 (2004). $^{2}$ \textit{Gaussian03}, Revision A.1, M. J. Frisch \textit{et al.,} Gaussian Inc., Pittsburgh, PA , 2003. $^{3 }$P. Pradhan and A. K. Ray, J. Mol. Structure (Theochem), in press.