Primitive cell
A primitive cell is a unit cell that contains exactly one lattice point. It is the
smallest possible cell.[5] If there is a lattice point at the edge of a cell and thus
shared with another cell, it is only counted half. Accordingly, a point located on
the corner of a cube is shared by 8 cubes and would count with 1/8.
In solid state physics, a primitive cell is a minimum volume cell (a unit cell) corresponding
to a single lattice point of a structure with discrete translational symmetry. The concept is
used particularly in describing crystal structure in two and three dimensions, though it
makes sense in all dimensions. A lattice can be characterized by the geometry of its
primitive cell.
The primitive cell is a primitive unit. A primitive unit is a section of the tiling (usually a
parallelogram or a set of neighboring tiles) that generates the whole tiling using only
translations, and is as small as possible.
The primitive cell is a fundamental domain with respect to translational symmetry only. In
the case of additional symmetries a fundamental domain is smaller.
2-dimensional primitive cell
A 2-dimensional primitive cell is a parallelogram, which in special cases may have
orthogonal angles, or equal lengths, or both.
2-dimensional primitive cells
Parallelogram Rhombus
(Orthorhombic) (Monocinic)
Rectangle Square
(Orthorhombic) (Tetragonal)
3-dimensional primitive cell
