First-principles calculations of barium hydride for hydrogen transport applications*

Barium hydride is one of several thermally stable alkaline earth hydrides (AeH$_2$; Ae = Sr, Ca, Ba) to hold potential interest for future hydrogen transport applications, based on its high conductivity of hydride ions over a broad temperature range. However, the underlying materials processes at play in promoting this conductivity remain to be elucidated. A greater understanding of the mechanisms enabling efficient hydride ion migration within BaH$_2$ is needed to move the material closer to applications. Toward that end, we conduct first-principles calculations based on density functional theory with a hybrid functional. We characterize the bulk electronic and structural properties of BaH$_2$ and study the mechanism of hydride ion migration and the influence of native point defects on ionic conductivity.