GaSi_n(n=1-6)团簇结构和稳定性的第一性原理研究

采用密度泛函理论(DFT),在B3LYP/6-311+G(d)水平下研究了GaSi_n(n=1-6)团簇的几何构型、电子性质、稳定性和振动特性.研究结果表明:GaSi_n(n=1-6)团簇基态结构基本保持了纯硅团簇的结构框架,Ga原子往往被吸附在Sin团簇的表面上.布局分析显示电子由Ga原子向Sin框架转移.平均束缚能和分裂能表明GaSi_3和GaSi_5团簇相对其他团簇具有较强的稳定性.振动特性研究表明:GaSi_n(n=1-6)团簇的IR活性最强振动模式主要是Ga原子与Sin结构之间的相对振动.极化率的研究表明,随着Si原子数的增多,GaSi_n团簇的非线形光学效应逐渐增强,更容易被外场极化.

First Principles Study on Geometries and Stabilities of Small GaSin(n=1-6) Clusters

The equilibrium geometries, electronic configurations, stabilities and vibrational properties of GaSin(n=1-6) clusters have been investigated at the B3LYP/6-311+G(d) level available in Gaussian03 program. Our calculations reveal that the most stable structure of GaSin (n=1-6) clusters basically keeps the analogous frameworks as the pure Sin+1 clusters, and the doped Ga atom is always adsorbed at a surface site. For the most stable isomers, charge transfer is found to proceed from Ga atom to the Sin framework; both the binding and fragmentation energies suggest that GaSi3 and GaSi5 have stronger stability. By investigating the vibrational properties, we have found that the maximal IR active vibrational frequencies of GaSin(n=1-6) clusters are attributed to the relative movements of the Ga atom and the Sin framework. With the increasing of Si atoms, GaSin clusters will have stronger nonlinear optical effect and be easier to polarize by external electromagnetic field.