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用密度泛函理论(DFT),在B3LYP/DZP水平上对H2O分子与VOx形成的团簇VOxH2O (x= 15)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= 15) 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= 15)团簇. VOxH2O (x= 15)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= 15) and interactions between H2O with VOx(x= 15) are studied by using the density functional theory B3LYP/DZP method. The results show that ground states for VOxH2O (x= 15) 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= 15) and VOxH2O(x= 15) are formed; In VOxH2O(x=15), 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= 15) is VO4H2O VO5H2O VOH2O VO3H2O VO2H2O; 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= 15) is obtained by analyzing frequency spectrum.
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Keywords:
- density-functional theory /
- stable frame /
- ground state /
- stability
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中国物理学会期刊
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