Density Functional Theory Calculations of Geometrical and Electronic Properties of Neutral and Charged Silicon Oxide Clusters

摘要

We investigate neutral and charged silicon oxide clusters (SinOn, n = 1-7) using density functional theory (DFT) calculations. For searching a local minimum structure of neutral, cationic, and anionic silicon oxide clusters, ab initio Monte Carlo (MC) simulations are used. Local minimum structures founded from simulations are again calculated using DFT calculations to find a global minimum structure. Relative energies based on total energy differences between the most stable structure and the possible isomers obtained from the calculation are reported. For studying structural properties of silicon oxide clusters, the PBE functional is used with DGDZVP and CEP-121G* basis sets. These basis sets are compared with each other and with the DGDZVP and 6-311 + G* basis sets, which are also compared with each other in terms of their electronic properties. Thus, the PBE/DGDZVP model is the best choice for large silicon oxide clusters calculations. Examinations are performed on the Si—O distances, Si-O-Si average bond angles, atomization energies per atom, second difference in energies, HOMO-LUMO gaps, adiabatic ionization potentials, and adiabatic electron affinities. All calculations use Gaussian09 program.