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  2. Crystallographic point group - Wikipedia

    en.wikipedia.org/wiki/Crystallographic_point_group

    These 32 groups are one-and-the-same as the 32 types of morphological (external) crystalline symmetries derived in 1830 by Johann Friedrich Christian Hessel from a consideration of observed crystal forms. In 1867 Axel Gadolin, who was unaware of the previous work of Hessel, found the crystallographic point groups independently using ...

  3. Timeline of crystallography - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_crystallography

    1826 - Moritz Ludwig Frankenheim derived the 32 crystal classes by using the crystallographic restriction, consistent with Haüy's laws, that only 2, 3, 4 and 6-fold rotational axes are permitted. [21] 1830 - Johann F. C. Hessel published an independent geometrical derivation of the 32 point groups (crystal classes). [22]

  4. Axel Gadolin - Wikipedia

    en.wikipedia.org/wiki/Axel_Gadolin

    Moritz Ludwig Frankenheim in 1826 and Johann F. C. Hessel in 1830 had found the 32 crystal classes. Gadolin, who was unaware of the work of his predecessors, [12] [13] found them independently using stereographic projection to represent the symmetry elements of the 32 groups. [14]

  5. Crystal system - Wikipedia

    en.wikipedia.org/wiki/Crystal_system

    A crystal system is a set of point groups in which the point groups themselves and their corresponding space groups are assigned to a lattice system. Of the 32 crystallographic point groups that exist in three dimensions, most are assigned to only one lattice system, in which case both the crystal and lattice systems have the same name. However ...

  6. Hermann–Mauguin notation - Wikipedia

    en.wikipedia.org/wiki/Hermann–Mauguin_notation

    The full and short symbols for all 32 crystallographic point groups are given in crystallographic point groups page. Besides five cubic groups, there are two more non-crystallographic icosahedral groups (I and I h in Schoenflies notation) and two limit groups (K and K h in Schoenflies notation). The Hermann–Mauguin symbols were not designed ...

  7. Crystal structure - Wikipedia

    en.wikipedia.org/wiki/Crystal_structure

    Of the 32 point groups that exist in three dimensions, most are assigned to only one lattice system, in which case the crystal system and lattice system both have the same name. However, five point groups are assigned to two lattice systems, rhombohedral and hexagonal, because both lattice systems exhibit threefold rotational symmetry.

  8. Point group - Wikipedia

    en.wikipedia.org/wiki/Point_group

    Point groups are used to describe the symmetries of geometric figures and physical objects such as molecules. Each point group can be represented as sets of orthogonal matrices M that transform point x into point y according to y = Mx. Each element of a point group is either a rotation (determinant of M = 1), or it is a reflection or improper ...

  9. List of space groups - Wikipedia

    en.wikipedia.org/wiki/List_of_space_groups

    The 54 hemisymmorphic space groups contain only axial combination of symmetry elements from the corresponding point groups. Example for point group 4/mmm (): hemisymmorphic space groups contain the axial combination 422, but at least one mirror plane m will be substituted with glide plane, for example P4/mcc (, 35h), P4/nbm (, 36h), P4/nnc ...