Materials Data on CaH2CO4 by Materials Project
CaCO3.H2O crystallizes in the trigonal P3_1 space group. The structure is three-dimensional. Ca2+ is bonded to eight O2- atoms to form a mixture of distorted edge and corner-sharing CaO8 hexagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.43–2.53 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.28 Å) and two longer (1.31 Å) C–O bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ca2+ and one C4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ca2+ and one C4+ atom. In the third O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Ca2+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ca2+ and one C4+ atom.