CO在α-U(001)表面的吸附  

CO Adsorption on α-U(001) Surface

作　　者：李赣[1] 罗文华[1] 陈虎翅[2] 

机构地区：[1]表面物理与化学国家重点实验室,四川绵阳621907 [2]中国工程物理研究院,四川绵阳621900

出　　处：《物理化学学报》2010年第5期1378-1384,共7页Acta Physico-Chimica Sinica

基　　金：国防科技重点实验室基金(9140C6601010901)资助项目~~

摘　　要：采用密度泛函理论中的广义梯度近似,计算了CO在α-U(001)表面的吸附、解离和扩散.结果表明:CO分子以CU3OU2构型化学吸附在α-U(001)表面,吸附能为1.78-1.99eV;吸附后表层U原子向上迁移,伴随着褶皱的产生;CO分子与表面U原子的相互作用主要是U原子的电子向CO分子最低空轨道2π*转移,以及CO2π*/5σ/1π-U6d轨道间杂化而生成新的化学键;CO解离吸附较分子吸附在能量上更为有利,h1(C)+h2(O)和h1(C)+h1(O)(h:空位)解离态吸附能分别为2.71和3.08eV;近邻三重穴位之间C、O原子的扩散能垒分别为0.57和0.14eV,预示O原子较C原子更易在U(001)表面扩散迁移.The adsorption,dissociation,and diffusion of CO on the α-U（001） surface were studied using density functional theory with the generalized gradient approximation（GGA）.The calculation results show that a CU3OU2-type molecular chemisorption of CO is favored with adsorption energies of 1.78-1.99 eV.The U atoms of the surface layer are found to move upwards after adsorption coupled with a rumpling of the surface layer.The interaction between the U atoms and a CO molecule results mainly from the population of the CO 2π＊ LUMO by U electrons and the CO 2π＊/5σ/1π-U 6d orbital hybridization.Dissociative adsorption is energetically more favored than molecular adsorption with adsorption energies of 2.71 and 3.08 eV for the h1（C）＋h2（O） and h1（C）＋h1（O）（h：hollow site） dissociative configurations,respectively.The diffusion barriers of C and O atoms between two adjacent threefold hollow sites are found to be 0.57 and 0.14 eV,respectively,which indicates that the on-surface diffusion of O atoms is more easily achieved than that of C atoms.

关 键 词：密度泛函理论 α-U(001)表面 CO 吸附 

分 类 号：O647.31[理学—物理化学]