Rock Salt and Diamond

In the following section, we will look in some more detail at the symmetry systems of two fundamentally important crystals, rock salt and diamond, following the descriptions by Shubnikov and Koptsik [31], The descriptions will be far from complete they will aim at giving some flavor for the characterization of these two highly symmetrical structures. 

Two very simple descriptions of the rock salt crystal structure are also given. According to one, the sodium and chloride ions occupy positions with point-group symmetry m3m forming a checkered pattern in the Fm3m space group. According to the other description, the structure consists of two cubic sublattices in parallel orientation, one of sodium ions and the other of chloride ions. 

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