D centred cell
From Online Dictionary of Crystallography
Maille centrée D (Fr). D-zentrierte Zelle (Ge). Cella centrata D (It). D 複合単位胞 (Ja). Celda (o red) centrada D (Sp).
The D centred cell is used for the rhombohedral description of the hexagonal lattice. Six right-handed D cells with basis vectors of equal length are obtained from the hP cell by means of one of the following transformation matrices:
D1: 10-1/01-1/111 D2: -101/0-11/111
The other four D cells are obtained by cyclic permutation of the basis vectors.
The resulting hD cell has centring nodes at 1/3,1/3,1/3 and 2/3,2/3,2/3.