Unit cell

Maille élémentaire (Fr). Einheitszelle (Ge);. Celda unidad (Sp); элементарная ячейка (Ru); Cella elementare (It); 単位胞（単位格子） (Ja).

Definition

The unit cell is the parallelepiped built on the vectors, a, b, c, of a crystallographic basis of the direct lattice. Its volume is given by the scalar triple product, V = (a, b, c) and corresponds to the square root of the determinant of the metric tensor.

If the basis is primitive, the unit cell is called the primitive cell. It contains only one lattice point. If the basis is non-primitive, the unit cell is a multiple cell and it contains more than one lattice point. The multiplicity of the cell is given by the ratio of its volume to the volume of a primitive cell.

See also

• conventional cell
• direct lattice
• primitive cell
• Section 8.1 of International Tables of Crystallography, Volume A