材料期刊网

We present a systematic first-principles investigation of the high-pressure structural stability of Li(2)BeH(4). Our total-energy calculations show that at ambient pressure, the structure of alpha-Li(2)BeH(4) observed in experiments is more stable than the other proposed structures in this work and the structural transformation from alpha to beta (Cs(2)MgH(4) type; Pnma) occurs at 18.1 GPa, together with a volume reduction of 4.7%. A detailed study of their electronic structures under ambient pressure up to 30.0 GPa reveals that this behavior is closely related to the variation in the Be-H covalent bonding in the BeH(4) anionic subunits of Li(2)BeH(4). Based on a colligated analysis of the covalent bond number per unit area (N(a)) and the scaled bond overlap population (BOP(s)), beta-NaAlH(4) and beta-Mg(AlH(4))(2) are expected to be the most promising candidates for hydrogen storage among the other investigated materials. However, the improvement of hydrogen absorption and/or desorption for Li(2)BeH(4) is less significant.