Density functional theory study of H, C and O chemisorption on UN(001) and(111) surfaces  

作　　者：李如松 何彬 许鹏 王飞 马文彦 

机构地区：[1]Xi’an Research Institute of Hi-Tech

出　　处：《Nuclear Science and Techniques》2014年第5期68-77,共10页核技术（英文）

基　　金：Supported by National Natural Science Foundation of China(Nos.51401237,51271198 and 11474358);Self-Topics Fund of Xi’an Research Institute of High Technology(Nos.2014QNJJ018 and YX2012cxpy06)

摘　　要：We performed density functional theory calculations of H, C, and O chemisorption on the UN(001) and(111) surfaces using the generalized gradient approximation(GGA) and the Hubbard U parameter and revised Perdew-Burke-Ernzerhof(RPBE) exchange-correlation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. distance of molecules from UN(001) and UN(111) surfaces have been optimized for four symmetrical chemisorption sites, respectively. The results show that the Hollow, N-top, and Hollow adsorption sites are the most stable sites for H, C, and O atoms with chemisorption energies of 13.06,25.50 and 27.34 kJ/mol for UN(001) surface, respectively. From the point of adsorbent(UN(001) and UN(111)surfaces in this paper), interaction of O with the chemisorbed surface is of the maximum magnitude, then C and H, which are in agreement with electronegativities of individual atoms. For the UN(001) surface, U-N bond lengths change relatively little(< 9%) as a result of H chemisorption, however C and O chemisorptions result in remarkable changes for U-N bond lengths in interlayer(> 10%). Electronic structure calculations indicate that Bridge position is equivalent with Hollow position, and the most stable chemisorption position for H, C,and O atoms are all Bridge(or Hollow) position for the UN(111) surface. Calculated electronic density of states(DOSs) demonstrate electronic charge transfer between s, p orbitals in chemisorbed atoms and U 6d, 5f orbitals.We performed density functional theory calculations of H, C, and O chemisorption on the UN（001） and （111） surfaces using the generalized gradient approximation （GGA） and the Hubbard U parameter and revised Perdew-Burke-Ernzerhof （RPBE） exchange-correlation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. distance of molecules from UN（001） and UN（111） surfaces have been optimized for four symmetrical chemisorption sites, respectively. The results show that the Hollow, N-top, and Hollow adsorption sites are the most stable sites for H, C, and O atoms with chemisorption energies of 13.06, 25.50 and 27.34 kJ/mol for UN（001 ） surface, respectively. From the point of adsorbent （UN（001） and UN（111） surfaces in this paper）, interaction of O with the chemisorbed surface is of the maximum magnitude, then C and H, which are in agreement with electronegativities of individual atoms. For the UN（001） surface, U-N bond lengths change relatively little （〈 9%） as a result of H chemisorption, however C and O chemisorptions result in remarkable changes for U-N bond lengths in interlayer （〉 10%）. Electronic structure calculations indicate that Bridge position is equivalent with Hollow position, and the most stable chemisorption position for H, C, and O atoms are all Bridge （or Hollow） position for the UN（1 11） surface. Calculated electronic density of states （DOSs） demonstrate electronic charge transfer between .9, p orbitals in chemisorbed atoms and U 6d, 5f orbitals.

关 键 词：化学吸附能 密度泛函理论 联合国 表面相互作用 吸附位置 广义梯度近似 电子结构 计算表 

分 类 号：O647.3[理学—物理化学]