(TiO_2)_n(n=3—6)团簇吸附水分子的理论研究  

Theoretical study of the adsorption of water molecule on (TiO_2)_n(n=3—6) clusters

作　　者：陈宏善[1] 孟凡顺[1] 李向富[1] 张素玲[1] 

机构地区：[1]西北师范大学物理与电子工程学院,兰州730070

出　　处：《物理学报》2009年第2期887-892,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10347007)资助的课题~~

摘　　要：给出了优化小分子在团簇表面吸附结构的遗传算法.结合经验势函数,搜寻了水分子在(TiO2)n(n=3—6)团簇上可能的吸附方式;利用B3LYP/6-31G**方法对各种吸附结构进行了优化.结果表明水分子主要通过O原子以非解离方式吸附到团簇中配位数较低或位置比较凸出的Ti原子上.分子轨道分析表明,水分子与团簇之间的成键主要来自吸附位Ti原子3s3p轨道的贡献,水分子的轨道保持了气相水分子中的基本特征,但离域化程度增大.NBO分析表明,Ti原子通过3sp向水中氧原子转移电荷,而水分子又通过轨道离域把电荷反馈到由Ti的3d4s等轨道形成的反键轨道.虽然吸附后水中O,H原子的净电量增加,但O—H键减弱.吸附后水分子的振动频率发生红移.Possible adsorption structures of H2O on （TiO2）n（n=3—6） clusters were studied by using genetic algorithm combined with empirical potential function. The structures were further optimized using DFT method B3LYP/6-31G^＊＊ . The results show that H_2O molecule is adsorbed on TiO_2 clusters through the attachment of oxygen atom to the titanium atom with lower coordination number. Molecular orbitals show that the bond between water and cluster is formed mainly by the 3s3p orbitals of titanium,the orbitals of H2O keep the basic features unchanged but are more delocalized after adsorption. Combined with population analysis and calculation of vibration frequencies,the results show that the O—H bond becomes weaker after H2O is adsorbed on TiO2 clusters.

关 键 词：TiO2团簇 H2O吸附 遗传算法 DFT 

分 类 号：O561[理学—原子与分子物理]