Ab initio investigation of LiNH$_{2}$, Li$_{2}$NH, and Mg(AlH$_{4}$)$_{2}$ complex hydrides

First-principles calculations on the complex hydrides LiNH$_{2}$, Li$_{2}$NH, and Mg(AlH$_{4}$)$_{2}$ were performed to determine their structural stability, electronic structure and formation energy. All these compounds were recently reported the most promising materials for reversible hydrogen storage. We discuss the ionic character and binding implications of other complex hydrides. Possibilities to improve the hydriding/dehydriding reactions are presented.