Sin/Si-n(n=2-6)的结构和电子亲合能的密度泛函理论研究

选用四种不同的密度泛函理论方法(B3LYP,BLYP,BP86,B3P86),在全电子的双ζ加极化加弥散函数基组(DZP++)下,研究Sin/Si-n (n=2 -6 )体系的结构和电子亲合能.预测Si2 /Si-2 ,Si3 /Si-3 ,Si4 /Si-4 ,Si5 /Si-5 和Si6 /Si-6 的基态结构分别为C∞h(3Σ-g ) /C∞h(2Σ+g ),D3h(3A′2 ) /C2υ(2A1 ),D2h(1Ag) /D2h(2B2g),D3h(1A′1 ) /D3h(2A″2 )和C2υ(1A1 ) /D4h(2A2u).在电子亲合能方面,B3LYP方法预测的电子亲合能是最可靠的.预测Si2,Si3,Si4,Si5和Si6的电子亲合能分别为 2. 05, 2. 34, 2. 16, 2. 48和 2. 13eV.

Study on Structure and Electronic Affinity of Silicon Cluster Sin/Si-n (n=2-6) with Density Functional Theory

Four different density functional theory (DFT) methods (B3LYP, BLYP, BP86, and B3P86) have been employed to predict the molecular structures and adiabaticelectronic affinities of the Si_(n)/Si~-_(n)(n=2-6) species. The basis used is of double-ζplus polarization quality with additional s- and p-type diffuse functions, labeled as DZP++. The ground states of Si_2/Si~-_2, Si_3/Si~-_3, (Si_(4)/Si~-_(4)), Si_(5)/Si~-_(5)and Si_(6)/Si~-_(6)are C_(∞h)(~3Σ~-_(g))/C_(∞h)(~2Σ~+_(g)), D_(3h)(~3A~′_2)/C_(2υ)(~2A_1), D_(2h)(~1A_(g))/D_(2h)(~2B_(2g)), D_(3h)(~1A~′_1)/D_(3h)(~2A~″_2) and C_(2υ)(~1A_1)/D_(4h)(~2A_(2u)), respectively. The B3LYP in all of these schemes is the best in respect of predicting electronic affinities. The electronic affinitiescorrected by zero-point vibrational energies for Si_2, Si_3, Si_(4), Si_(5), and Si_(6)are 2.05, 2.34, 2.16, 2.48, and 2.13 eV, respectively.