中性和带电小钨团簇的第一性原理研究

采用基于密度泛函理论的第一性原理方法，计算了中性和带电小钨团簇W_n（n＝3—6）的构型，得到了一些能量较低的结构，它们都有可能是团簇的基态.研究发现，这些团簇大多具有较低的自旋多重度：中性小钨团簇为自旋单态或三重态；带电小钨团簇为自旋双重态或四重态.当n>3时，小钨团簇具有三维立体结构.通过拟合光电子谱、计算垂直离化能并与实验值比较，进一步讨论了带负电小钨团簇的基态结构. 关键词： 小钨团簇 构型 密度泛函理论

First principles study of neutral and charged small tungsten clusters

Geometries of anionic, neutral and cationic small tungsten clusters W_n （n=3—6） are studied by the first principles method based on the density functional theory. For each of clusters studied, a number of low-lying states with specific geometries are found and some possible candidates for the global minimum are determined. It is found that all global minimum candidates have relatively low spins: singlet or triplet for the neutral clusters, and doublet or quartet for the ionic clusters. When n>3, the clusters undergo a transition from two-dimensional structure to three-dimensional structure, which is not the same as sliver clusters. In order to determine the most promising global minimum candidates for anionic clusters, the photoelectron spectra are simulated and the vertical detachment energy is calculated. All results obtained are in good agreement with available experimental data.