No abstract

Chemically speaking, atomic clusters are very rich, allowing their application in a broad range of technological areas such as developing functional materials, heterogeneous catalysis, and building optical devices. In this work, high level computational chemistry methods were used in a systematic manner to improve the characterization of small clusters formed by boron, silicon, germanium, mixed boron/silicon, and mixed boron/germanium. Calculations were carried out with both ab initio [MP2 and CCSD(T)] and density functional (B3LYP) methods with extended basis sets. The CCSD(T) results were then extrapolated to the complete basis set (CBS) limit. Finally, geometrical parameters, vibrational frequencies, and relative energies were then obtained and compared to data presented in the literature. Graphical Abstract Small boron, silicon and germanium clusters: BmSin and BmGen (m + n = 2-4).

ABSTRACT:The main objective of this study consists in providing reliable structures, harmonic vibrational frequencies, and relative electronic energies of Si 3 , GeSi 2 , Ge 2 Si, and Ge 3 clusters using DFT, CCSD(T), CASSCF, and MP2 methods and extended basis sets. The CCSD(T) results are extrapolation to the complete basis set (CBS) limit. For Si 3 cluster, the ground-state is a singlet ( 1 A 1 ) and the lowest lying electronic state is triplet state ( 3 A 0 2 ) separated by 0.44 kcal mol À1 at the CCSD(T)/(CBS) limit. The ground-states of GeSi 2 , Ge 2 Si, and Ge 3 clusters are also singlet state with triplet states very close energetically. Computed equilibrium geometries and vibrational frequencies are compared with previous theoretical and experimental data.