Condensed matter physics MOC Crystallographic group A crystallographic group or space group in dimension is a discrete subgroup of the Euclidean group containing a normal -lattice subgroup such that quotient group , called the Point group, is a subgroup of the real orthogonal group . #m/def/group This gives the following pair of short exact sequences Such a group is the symmetry group of a Crystal. According to the Crystallographic restriction theorem, point groups must have rotational symmetries that are 1-,2-,3-,4-, or 6-fold. #state/develop | #lang/en | #SemBr