We illustrate a systematic search method for determining hydrogen atomic arrangements in the hydrogen storage material, Li2 NH. Our method relies on total-energy density-functional calculations, and yields a minimum-energy crystal structure for Li2 NH as well as several low-energy metastable structures. Linear-response calculated Born effective charges show strong ionic interactions between the Li and N-H dimers, while the bonding between the N and H has covalent character. Including vibrational contributions, our orthorhombic Pnma structure yields a hydrogen storage Li2 NH LiN H2 reaction enthalpy of 63.7 kJ mol H2 at T=0 K, and 74.8 kJ mol H2 at T=300 K, in good agreement with experimental reports of ∼66 kJ mol H2 for this reaction.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jun 14 2006|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics