Theoretical study of the CsMgH 3 , Cs 2 MgH 4 and Cs 4 Mg 3 H 10 complex hydrides from first‐principles

Theoretical investigation of structure, reaction enthalpies and electronic properties of the CsMgH 3 , Cs 2 MgH 4 , and Cs 4 Mg 3 H 10 compounds were performed using the first‐principles method within generalized gradient approximation. The obtained lattice constants and position coordinates of atoms for the systems were in good agreement with experimental results. The calculated reaction enthalpies for CsMgH 3 , Cs 2 MgH 4 , and Cs 4 Mg 3 H 10 showed that the ternary hydrides can be synthesized thermodynamically by direct reaction between Cs and Mg in hydrogen atmosphere and by appropriate combination of binary hydrides. The energy band structure and electronic density of states revealed that all of the compounds are wide‐band‐gap insulators. The electronic DOS together with charge‐density redistribution implied the significant charge transfer leading to Cs + ions and negatively charged [MgH 6 ] 4– complex, and the dominant ionic character with noticeable covalence between Mg and H in the [MgH 6 ] 4– anionic complexes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)