On the structural and energetic properties of the hydrogen absorber Li2 Mg (NH)2

The authors have performed density functional theory based calculations of several possible conformations for the crystal structure of Li2 Mg (NH)2 and they confirm the α phase, resolved from both x-ray and neutron diffraction data, as the ground-state configuration. It is also found that although the N-H bond is stronger in Li2 Mg (NH)2 than in Li2 NH, hydrogen release from Li2 Mg (NH)2 LiH mixture displays more favorable thermodynamics than that from the Li2 NHLiH mixture. The insights gained from this seemingly counterintuitive result should prove helpful in the search for promising hydrogen storage materials. © 2007 American Institute of Physics