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

• Published in: International journal of hydrogen energy Vol. 37; no. 6; pp. 5108 - 5113
• Main Authors: Ao, B.Y., Wang, X.L., Shi, P., Chen, P.H., Ye, X.Q., Lai, X.C., Ai, J.J., Gao, T.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2012
• Subjects: Atomic radius; Cerium hydride; Crystal structure; Density functional theory; Strongly-correlated electron system; Density functional theory; Cerium hydride; Strongly-correlated electron system; Crystal structure
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2011.12.095

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 (CeHx, 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.
► Abnormal lattice contraction of Ce hydrides with increasing H is reproduced. ► Strong Coulomb correlation between localized 4f electron is reasonably considered. ► Contraction of lattice parameter results from the electronic and structural effects.