Structural transition of $LiBeH_3$ under high pressure

Abstract

$LiBeH_3$ has been considered as a solid-state hydrogen storage material. This study investigated Pnma orthorhombic phase of $LiBeH_3$ under pressure. Ab initio constant pressure molecular dynamic simulation under pressure was adopted. The results depicted a phase transition from Pnma orthorhombic phase to $P2_1/m$ monoclinic phase at 270 GPa simulation pressure. The stability of each phase was examined using elastic constants. Based on the well-known Born stability criteria, both phases showed mechanical stability. Several moduli have been computed via elastic constants. The B/G ratios, Cauchy pressures and Poisson’s ratios investigation revealed that $LiBeH_3$ is brittle at Pnma phase whereas it is ductile at $P2_1/m$ phase. The electronic band structures and partial and total density of states of phases were also obtained. A 2.058 eV band gap was seen for Pnma phase, and 3 eV band gap was seen for $P2_1/m$ phase.