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Wilhelm Röntgen, India, 1995. Stamps depicting individual crystallographers are sometimes issued by countries to commemorate the birth or death anniversaries of their significant national crystallographers, [12] For example, on August 6, 1996, the British postal service (Royal Mail) issued a stamp honouring Dorothy Hodgkin, a pioneer of protein crystallography (Great Britain's first female ...
The symbol of a space group is defined by combining the uppercase letter describing the lattice type with symbols specifying the symmetry elements. The symmetry elements are ordered the same way as in the symbol of corresponding point group (the group that is obtained if one removes all translational components from the space group).
In Schoenflies notation, point groups are denoted by a letter symbol with a subscript. The symbols used in crystallography mean the following: C n (for cyclic) indicates that the group has an n-fold rotation axis. C nh is C n with the addition of a mirror (reflection) plane perpendicular to the axis of rotation.
The Pearson symbol, or Pearson notation, is used in crystallography as a means of describing a crystal structure. [1] It was originated by W. B. Pearson and is used extensively in Peason's handbook of crystallographic data for intermetallic phases. [2] The symbol is made up of two letters followed by a number. For example: Diamond structure, cF8
In crystallography, a Strukturbericht designation or Strukturbericht type is a system of detailed crystal structure classification by analogy to another known structure. The designations were intended to be comprehensive but are mainly used as supplement to space group crystal structures designations, especially historically.
The Wyckoff positions are named after Ralph Wyckoff, an American X-ray crystallographer who authored several books in the field.His 1922 book, The Analytical Expression of the Results of the Theory of Space Groups, [3] contained tables with the positional coordinates, both general and special, permitted by the symmetry elements.
However, in crystallography, there is additional translational symmetry, and point groups are not enough to describe the full symmetry of crystals, so the full space group is usually used instead. The naming of full space groups usually follows another common convention, the Hermann–Mauguin notation , also known as the international notation.
The objectives of the IUCr are to promote international cooperation in crystallography and to contribute to all aspects of crystallography, to promote international publication of crystallographic research, to facilitate standardization of methods, units, nomenclatures and symbols, and to form a focus for the relations of crystallography to other sciences.