In crystallography, space groups 1 2 represent a description of the symmetry of the crystal structure, generated by the symmetric repetition of an atomic grouping which, by itself, may or may not be symmetrical. There are 230 space groups in total, and each crystal structure existent in nature belongs to one of them.
In its simplest form, a space group may be derived from translational symmetry. It can be developed further by incorporating additional more complex symmetry elements, such as mirror planes, rotations, screw axes and glide planes.
Space Groups are labelled by a distinctive notation convention, as tabulated in Ref. 3. For example, the space group of the cubic-diamond crystal structure, which silicon, germanium and carbon (diamond) share in common, is labelled by the symbol "Fd-3m".
The JSON schema and an example representation for this property can be found here.