# H centred cell

### From Online Dictionary of Crystallography

Maille centrée H (*Fr*). H-zentrierte Zelle (*Ge*). Cella centrata H (*It*). H 複合単位胞 (*Ja*). Celda centrada H (*Sp*).

The ** H centred cell** (

**triple hexagonal cell**) is an alternative description of the hexagonal Bravais lattice. From the conventional

*hP*cell one obtains the

*hH*cell by taking the new basis vectors by means of one of the following transformation matrices, which give three possible orientations of the

*hH*cell with respect to the

*hP*cell:

*H*_{1}: 110/-120/001 *H*_{2}: 2-10/110/001 *H*_{3}: 1-20/2-10/001

The resulting *hH* cell has centring nodes at 1/3,2/3,0 and 2/3,1/3,0.

Secondary and tertiary elements in the *hP* cell are exchanged in the *hH* cell. For example, the space-group symbol *P*3*m*1 become *H*31*m* when the triple cell is used.

## See also

- Centred lattices
- D centred cell
- Chapter 1.5 of
*International Tables for Crystallography, Volume A*, 6th edition