Dynamical stability of the cubic metallic phase of AlH3 at ambient pressure

We have characterized the high-pressure cubic phase of AlH$_{3}$ using density functional theory to determine mechanical as well as electronic properties and lattice dynamics from the response function method [1]. Metallization in AlH$_{3}$ under pressure has been studied, which is of great interest not only from a fundamental physics point of view for the study of phenomena related to metallic hydrogen, but also, because metallic AlH$_{3}$ possesses weaker Al-H bonds than other insulating phases [2]. Our phonon calculations show the softening of a particular mode with decreasing pressure, indicating the onset of a dynamical instability that continues to persist at ambient conditions. We find from analyzing the atomic and electronic interactions using theoretical calculations that finite-temperature effects lead to the desired stabilization of metallic AlH$_{3}$ at ambient conditions.\\[0pt] [1] PRB \textbf{78}, 100102(R) (2008). \\[0pt] [2] APL \textbf{92}, 201903 (2008).