Materials Data on CaH2 by Materials Project
CaH2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ca2+ is bonded in a 3-coordinate geometry to eleven H1- atoms. There are a spread of Ca–H bond distances ranging from 2.20–2.67 Å. There are two inequivalent H1- sites. In the first H1- site, H1- is bonded to five equivalent Ca2+ atoms to form distorted HCa5 trigonal bipyramids that share corners with twelve equivalent HCa6 octahedra, corners with eight equivalent HCa5 trigonal bipyramids, edges with six equivalent HCa5 trigonal bipyramids, and faces with six equivalent HCa6 octahedra. The corner-sharing octahedra tilt angles range from 31–59°. In the second H1- site, H1- is bonded to six equivalent Ca2+ atoms to form HCa6 octahedra that share corners with twelve equivalent HCa6 octahedra, corners with twelve equivalent HCa5 trigonal bipyramids, edges with six equivalent HCa6 octahedra, faces with two equivalent HCa6 octahedra, and faces with six equivalent HCa5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°.