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H2在MgO团簇吸附的从头计算研究
Adsorption of H2 on MgO clusters studied by ab initio method
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摘要: 根据最稳定幻数MgO团簇的结构特点，对H2在岩盐和管状结构（MgO）9,12表面的吸附性质进行了从头计算研究．结果表明H2可以在处于团簇不同位置的Mg正离子或氧负离子上发生物理吸附；在Mg离子上H2以侧位方式吸附并向Mg转移电子，在O离子上H2以端位方式吸附并被明显极化．吸附的稳定性主要依赖于吸附离子的位置即配位数，Mg／O离子的配位数越低则吸附越强；在配位数相同时，H2在Mg离子上的吸附强于在O离子上的吸附．随吸附位置的不同，吸附能在0．03-0．08eV．计算结果与最近H2在MgO块体表面吸附的实验结果一致．Abstract: Based on the most stable structures of the magic MgO clusters, the adsorption of H2onto the rocksalt and hexagonal tube （MgO）9,12 is studied using first principal method. The results show that physical adsorption can be formed on Mg ^＋q or O^-q ions at different sites of the clusters. On the top of the Mg^＋q ions, H2 is adsorbed in the side-on manner and donates electrons to the ions. On the top of the O^-9 ions, H2 is adsorbed in the end-on manner and the molecule is polarized. The strength of the adsorption depends mainly on the location of the Mg/O ions, and the smaller the coordination number of the ions, the stronger the adsorption of H2 is. For the Mg/O ions with the same coordination number, the adsorption formed onto the Mg^＋q is stronger. According to the Mg or O ions and their locations, the adsorption energy ranges from 0.03 eV to 0.08 eV.
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