| Hybrid density functional theory has been used to study the electronic and geometric structure properties of silicon-germanium nanoclusters containing up to eight atoms. The hybrid functional used is Becke's three-parameter exchange functional with the exchange-correlation functional of Lee, Yang, and Parr (B3LYP). A large 6-311G(3df,3pd) basis set as implemented in the suite of software Gaussian 03/09 has been used for accurate determinations of all properties of the SimGen (m + n ≤ 8) nanoclusters. For each cluster, various different isomers have been studied to arrive at a global minimum energy structure, and for each of these isomers we report our results on bond lengths, symmetry group, electronic state, binding energy per atom, HOMO-LUMO gap, and dipole moment. We also report results on vertical ionization potential, adiabatic ionization potential, vertical electron affinity, and adiabatic electron affinity. Results have been compared with available experimental results. Finally, for the lowest energy isomers, harmonic frequencies, fragmentation energies, average coordination numbers, and Mulliken atomic charges have been calculated. |
