【作者】 彭平； 李贵发；

【机构】 湖南大学材料科学与工程学院；

【摘要】 通过对生成物的结构微调来设定反应物、基于CI-NEB方法确定的最低能量路径MEP、在Dmol3软件中应用同步转变与二次同步转变LST/QST程序进行过渡态TS搜索,一种新的高稳定性的Al₁₂C团簇的结构形态Cs-Al₁₂C被发现。通过与Al₁₂C团簇基态二十面体Ih-Al₁₂C构型的能态与电子结构的比较,以及这两种形态结构被合成难易程度的分析,预测Cs-Al₁₂C更容易通过Al晶体在甲烷气氛下被气化合成。相对于Ih-Al₁₂C构型,Cs-Al₁₂C结构形态的计算结果与Al₁₂C光电子吸收谱等实验分析数据的符合程度更好。更多还原

【Abstract】 The energetics and electronic structures of several Al₁₂C configurations as well as their configuration evolution are investigated by a molecular orbital DMol³ program based on density functional theory,with the aid of the minimum energy path（MEP） in the climbing image nudged elastic band method（CI-NEB）.A new low symmetrical isomer of Al₁₂C cluster,i.e.,C s-Al₁₂C,at a local minimum in the MEPs is detected.Several parameters,such as the binding energy E_b,the HOMO-LUMO energy gapΔE_H-L,the electron affinity E_EA and the vertical electron detachment energy E_VDE,are adopted to characterize and evaluate the stability of Al₁₂C configurations.The C atom in the Cs-Al₁₂C configuration is demonstrated to locate above a surface consisting of four Al atoms and some covalent bonds exist between the C and its four Al neighbors.The difference in E_b between Cs-Al₁₂C and Ih-Al₁₂C configurations is proved to be very small.Different from the Ih icosahedron,the calculated E_EA and E_VDE of neutral Cs-Al₁₂C configuration and the absorption spectra of anionic Cs-Al₁₂C clusters are in good agreement with experimental data. The configuration evolution from neutral Cs-Al₁₂C to neutral Ih-Al₁₂C and the synthesis preference in the mode of Al₁₂+C→Al₁₂C reveal Cs-Al₁₂C configuration can coexist with ground-state Ih-Al₁₂C structure in energetics and the Cs-Al₁₂C configuration has a high formation ability compared with Ih-Al₁₂C structure.更多还原