A Density Functional Study of α-Mg(BH₄)₂

Boranates (tetrahydroborates) are studied intensively because of their potential use as hydrogen storage materials. In this Article, we present a first-principles study of α-Mg(BH 4 ) 2 at the level of density functional theory. We optimize the complex structure of α-Mg(BH 4 ) 2, starting from the experimental crystal structures with 30 formula units per unit cell. From total energy calculations, incorporating vibrational contributions at finite temperature, we show that the hydrogen desorption reaction α-Mg(BH 4 ) 2 → MgB 2 + 4H 2 has a reaction enthalpy of 38 kJ/mol H 2 at room temperature. This makes Mg(BH 4 ) 2 an interesting candidate as a hydrogen storage material.