第一性原理研究掺杂及未掺杂(TiO2)3团簇的电子性质

为了研究金属掺杂团簇时带隙的变化趋势，本文用Cr, Mo, V, Nb四种元素掺杂 (TiO2)3团簇，并用密度泛函理论下的广义梯度近似（GGA）方法计算。不同掺杂位置的结果表明最好的掺杂位置是3-配位的钛位置。所有掺杂后(TiO2)3团簇的HOMO-LUMO带隙都要比未掺杂时要小，对应高能区态密度峰值左移0.1eV；HOMO的电子云分布主要占据了氧原子的位置，当掺杂团簇被激发时，电子从末端氧原子位置跃迁到掺杂原子。此外，我们进一步的计算表明Cr和Mo是降低(TiO2)3团簇带隙较好的掺杂元素。为了进一步的研究掺杂(TiO2)3团簇的性质以及它在光催化，清洁能源等方面的应用，还需要我们进行实验和理论相结合的研究。

Electronic Properties of Bare and Doped (TiO2)3 Cluster--- A Density Functional Theory Investigation

This paper calculated the X-doped(X=Cr, Mo, V, Nb) titanium dioxide clusters model on the base of the anatase structure, in order to establish a qualitative trend to reduce the band gap by doping transition metals, we used the generalized gradient approximation(GGA) method under density functional theory. Computing tests of different doped positions show that the preferred Cr-, Mo-, V- or Nb-doping site is the 3-fold Ti site on the exterior side. For all the Cr-, Mo-, V- and Nb doped (TiO2)3 clusters, the HOMO-LUMO energy gaps are lower than that of the undoped one, the corresponding DOS peaks shift to the left side about 0.1eV in the high energy region, and the electron density distribution of HOMO orbital mainly occupy the oxygen site, with electrons transfer from the terminal suspension oxygen atoms to the doped transition metal atoms when the dopants are excited. Furthermore, our detailed calculations show that Cr- and Mo- are the best dopants for reducing the band gap of the (TiO2)3 clusters. To fully understand the properties of these doped materials and consider for applications, such as photocatalysis or clean energy production, further experimental and theoretical investigations are needed.