The search for novel hydrogen storage materials: a theoretical approach

Density Functional Theory (DFT) is a powerful tool to predict the crystal structure of hitherto experimentally unknown phases. In this article, we demonstrate the predicting capability of DFT on the structural properties of hydrogen storage materials from different input structure models. An experimentally known structural framework is successfully reproduced for NaMgH3 and the positional and unit-cell parameters are found to be in good agreement with the experimental findings. The crystal structure of LiMgH3 has been predicted and this compound should have ferroelectric properties. The calculated phonon spectrum indicates that LiMgH3 is an energetically and thermodynamically stable phase. A pressure-induced structural transition has been identified for this phase and it transforms into CaCO3-type modification at 38 GPa.