Lattice contraction of cerium hydrides from first-principles LDA?+?U calculations

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• 作者：B.Y. Ao^a ; ^{aobingyun24@yahoo.com.cn} ; X.L. Wang^a ; P. Shi^a ; P.H. Chen^a ; X.Q. Ye^a ; X.C. Lai^a ; J.J. Ai^b ; T. Gao^b ; ^{gaotao@scu.edu.cn}
• 关键词：Cerium hydride ; Density functional theory ; Strongly-correlated electron system ; Crystal structure
• 刊名：International Journal of Hydrogen Energy
• 出版年：2012
• 出版时间：March, 2012
• 年：2012
• 卷：37
• 期：6
• 页码：5108-5113
• 全文大小：730 K

文摘

Ce can be loaded with H forming complicated continuous solid solution and compounds, and causing remarkable electronic-structure changes. First-principles pseudopotential plane wave method with adding a Hubbard parameter U for considering the strong Coulomb correlation between localized 4f electron is employed to investigate the electronic and structural properties of stoichiometric and nonstoichiometric face-centered cubic (fcc) Ce hydrides (CeH_x, x?=?2, 2.25, 2.5, 2.75 and 3, respectively.). The most remarkable result is the decreasing trend of the calculated lattice parameters with increasing H composition, which is resulted from the associated effects of the enhanced chemical bonding owing to the participation of Ce 5d electron and, the size effects owing to the small H atomic radius and the large volume of octahedral interstice thus in favor of reducing the atomic distance for the formation of chemical bonding between Ce and octahedral H atoms.