1.100: Subperiodic group
A
subperiodic group
is a group of Euclidean mappings such that its translations form a lattice in a proper subspace of the space on which it acts.
A
crystallographic subperiodic group
in n-dimensional space is a subperiodic group for which the group of linear parts is a crystallographic point group of n-dimensional space. The crystallographic subperiodic groups in two and three-dimensional space are classified in:
- frieze groups : 7 two-dimensional groups with one-dimensional translations;
- rod groups : 75 three-dimensional groups with one-dimensional translations;
- layer groups : 80 three-dimensional groups with two-dimensional translations.