VO_xH_2O(x=1-5)团簇的结构及稳定性研究

Structures and stabilities of VO_xH_2O(x=1-5) clusters

用密度泛函理论（DFT）,在B3ILYP/DZP水平上对H2O分子与VOx形成的团簇VOxH2O（x=1—5）进行结构优化、能量和频率的计算,研究了团簇的稳定结构、稳定性和频率特性.结果表明VOxH2O（x=1—5）团簇的基态构型的电子态均为~2A,对称性均属C1对称点群,其中x=1,4,5时基态构型中水分子已被解离.水分子倾向于吸附在团簇VOx上,形成VOxH2O（x=1—5）团簇.VOxH2O（x=1—5）团簇中,VOxH2O（x=1,4,5）的化学活性小于VOxH2O（x=2,3）的化学活性.此外,H2O）体系与VOx之间的结合强弱顺序为VO4H2O〉VO5H2O〉VOH2O〉VO3H2O〉VO2H2O.VOH2O中离解出H原子的能量为2.88 eV和从VO5H2O中离解出OH基团的能量为2.38 eV,均在可见光能量范围内,这两个化学过程有可能在可见光催化条件下进行.可以通过团簇的红外和拉曼谱特征,初步判断水分子在VOxH2O团簇中是否离解.

The equilibrium geometries,vibrational frequencies of VOxH2O（x=1-5） and interactions between H2O with VOx（x = 1-5） are studied by using the density functional theory B3LYP/DZP method.The results show that ground states for VOxH2O（x = 1-5） belong to C1 point group symmetry,their electronic state is ~2A,and in ground state of VOxH2O（x = 1,4,5） water molecule H2O is dissociated;H2O molecule is absorbed easily in VOx（x = 1-5） and VOxH2O（x=1-5） are formed;In VOxH2O（x =1-5）, chemical activations of VOxH2O（x = 1,4,5） are lower than those of VOxH2O（x = 2,3）;the sequence of interaction strength between H2O and VOx（x = 1-5） is VO4H2OVO5H2OVOH2OVO3H2OVO2H2O;there is possibility that OH segment and H atom are dissociated easily from VOH2O and VO5H2O,respectively by visible light exposure.Criterion that H2O molecule is dissociated in VOxH2O（x = 1-5） is obtained by analyzing frequency spectrum.