Structural and Electronic Properties of Binary Clusters SimGen (m + n = 6–13)

Abstract

Using genetic algorithm combined with density functional theory calculations, we performed an unbiased global search for the most-stable structures of binary clusters SimGen with size s = m + n from 6 to 13. Further, we studied the structural and electronic properties of SimGen clusters using the B3LYP and CCSD(T) methods coupled with 6-311G + (d) basis set. For s = 6-12, SimGes-m clusters exhibit similar geometries to Sis and Ges clusters, respectively. However, for s = 13, the geometries of SimGes-m clusters fall into five completely different patterns. The negative mixing energies of SimGes-m clusters indicate that they possess higher energetic stability than Sis and Ges clusters. Among all clusters investigated, Si₂Ge₄, Si₂Ge5, Si₂Ge6, Si6Ge₃, Si5Ge5, Si7Ge₄, Si₃Ge9, and Si8Ge5 clusters have the relatively lower mixing energies and thus the highest energetic stabilities. Moreover, the Si₂Ge₄, Si₂Ge6, Si5Ge5, Si7Ge₄, and Si8Ge5 clusters with higher HOMO-LOMO gaps should have higher chemical stabilities than the same-sized Sis and Ges clusters. The Si5Ge5 cluster has a higher ionization potential than Si10 and Ge10. At the size s = 13, the geometry with the highest symmetry has the highest energetic and chemical stabilities.