中文摘要：

采用密度泛函理论（DFT）与耦合簇[CCSD（T）]相结合的计算方法对一系列二核铪氧簇合物Hf_2O_n（–/0）（n=1～6）的电子结构进行了系统研究.通过密度泛函理论（DFT）计算对体系的势能面进行广泛的搜索,寻找能量最低的结构.采用广义Koopmans定理计算垂直电子逸出能（VDEs）并模拟阴离子光电子谱（PES）.通过理论研究阐明了二核铪氧簇Hf_2O_n（–/0）（n=1～6）结构演化规律,并利用分子轨道分析对二核铪氧簇Hf2On–（n=1～4）的化学成键和顺序氧化进行解释.自旋密度分析显示：除Hf_2O_5中性簇之外,其它富氧簇都存在多种类型的氧自由基：氧自由基、双自由基或超氧自由基.此外,研究发现Hf2O3中性簇中的定域Hf2＋位容易与分子氧O2反应形成Hf_2O_5中性簇; Hf_2O_4（–/0）簇合物与分子O_2作用形成Hf_2O_6（–/0）簇合物,Hf_2O_4（–/0）簇合物可以作为潜在的分子模型研究氧分子在铪氧化物上的活化.

英文摘要：

Extensive density functional theoretical（DFT） and ab initio [CCSD（T）] calculations were combined to investigate the geometric and electronic structure of a series of dinuclear hafnium oxide clusters, Hf_2O_n（–/0）（n=1～6）. DFT calculations were performed to search for the lowest energy structures for both the anionic clusters and the neutral counterparts. The search for the global minima was performed using analytical gradients with the Stuttgart relativistic small core potential and the valence basis sets augmented with two f-type and one g-type polarization functions for Hf and the aug-cc-p VTZ basis set for oxygen. The relative energies of the low-lying structures（within ca. 0.35 e V） were further evaluated via single-point calculations at the coupled cluster [CCSD（T）] level with the Hf/Stuttgart＋2f1g/O/aug-cc-p VTZ basis sets at the B3 LYP geometries. Generalized Koopmans＇ theorem（GKT） was applied to predict VDEs and simulate the anion photoelectron spectra（PES）. The trends of structural evolution and the behavior of sequential oxidation of the Hf_2On–（n=1～6） clusters were observed. For the anionic species, starting from the C_2 v triangular structure Hf_2O–, the next O atom in the Hf_2O_2– cluster was again bridge-bonded, forming a rhombus structure. The third O atom occupied the terminal site. The fourth O atom favored the bridging site and the fifth O atom occupied the terminal site. In Hf_2O_6–, the additional O atom was bonded to a terminal site. Molecular orbital analyses were performed to elucidate the chemical bonding and the structural evolution in Hf2On–（n=1～4） clusters. Spin density analyses revealed oxygen radical, diradical and superoxide characters in the oxygen-rich clusters, except for the singlet Hf_2O_5 cluster. We showed that Hf_2O_3 contains a localized Hf（2＋） site, which can readily react with O_2 to form the Hf_2O_5 cluster. The Hf_2O_6– and Hf_2O_6 clusters, which can be viewed to be formed by the interaction of Hf_2O_4