International
Tables for
Crystallography
Volume A
Space-group symmetry
Edited by M. I. Aroyo

International Tables for Crystallography (2015). Vol. A, ch. 1.4, pp. 45-46

## Section 1.4.1.4.3. Triclinic space groups

H. Wondratscheke

#### 1.4.1.4.3. Triclinic space groups

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There is no symmetry direction in a triclinic space group. Therefore, the basis vectors of a triclinic space group can always be chosen to span a primitive cell and the HM symbols are P1 (without inversions) and (with inversions). The HM symbol is the only one which displays the inversion explicitly. Sometimes non-conventional centred lattice descriptions may be used, especially when comparing crystal structures.