First principles investigations of the hydrogenation effects on the electronic structure and the chemical bonding of CeIrAl

Hydrogenation of CeIrAl, leading to CeIrAlH2, induces both changes of the crystal and electronic structure that we address within the density functional theory. The ab initio positioning of hydrogen leads to its coordination within Ce3Ir tetrahedra and allows reproducing and interpreting the experimental findings of a Ce valence change from intermediate to trivalent in CeIrAlH2 through the bonding of hydrogen with Ce and Ir. From Bader analysis of the charge density, hydrogen carries a charge of -0.39 and is found from energy differences to be weakly and covalently bonded in the intermetallic substructure. The results allow assessing the reversibility of hydrogen absorption/desorption in CeIrAl. (C) 2011 Elsevier Masson SAS. All rights reserved.