Si3N4团簇结构与性质的密度泛函理论研究

用杂化密度泛函B3LYP在6-31G*的水平上研究了Si3N4团簇可能结构的平衡几何构型和电子结构,得到了24个可能的异构体.Si3N4团簇的最稳定结构是由7个Si—N键和2个N—N键形成的3个四边形构成的三维结构.用自然键轨道方法(NBO)分析了成键性质,结果表明,Si—N键中的Si、N原子的净电荷较大,说明Si—N键中Si、N原子的相互作用主要是电相互作用.最强的IR和Raman峰分别位于1033.40 cm-1,473.63 cm-1处.并且讨论了最稳定结构的极化率和超极化率.

Density functional theory study on the structure and properties of Si3N4 clusters

The hybrid density functional theory B3LYP with basis sets 6-31G~* has been used to study on the equilibrium geometries and electronic structures of possible isomers of Si_3N_4 clusters.24 possible isomers are obtained.The most stable isomer of Si_3N_4 is a 3D structure with 7 Si-N bonds and 2 N-N bonds that could be formed by 3 quadrangles.The bond properties of the most stable isomer was analyzed by using natural bond orbital method(NBO),the results suggest that the charges on Si and N atoms in Si-N bonds are quite large,so the interaction of N-Si atoms in Si_3N_4 cluster is of strongly electric interaction.The primary IR and Raman vibrational frequency located at 1033.40 cm~-1,473.63 cm~-1 respectively.The polarizabilities and hyperpolarizabilities of the most stable isomer are also analyzed.