 Crystallographic restriction theorem

The Crystallographic Restriction Theorem is a concept in the field of crystallography and solid state physics that describes certain symmetries in crystalline materials. It states that the symmetry operations of a crystal, such as rotations, translations, and reflections, impose restrictions on the types of point groups that can be realized in three-dimensional space. More specifically, the theorem states that the only symmetry operations allowed for a crystal lattice in three dimensions must be compatible with the periodicity of the lattice.