Search results
Results From The WOW.Com Content Network
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.
In Hermann–Mauguin notation, space groups are named by a symbol combining the point group identifier with the uppercase letters describing the lattice type.Translations within the lattice in the form of screw axes and glide planes are also noted, giving a complete crystallographic space group.
It has a shortened form called the international short symbol, which is the one most commonly used in crystallography, and usually consists of a set of four symbols. The first describes the centering of the Bravais lattice ( P , A , C , I , R or F ).
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
The wurtzite crystal structure is referred to by the Strukturbericht designation B4 and the Pearson symbol hP4. The corresponding space group is No. 186 (in International Union of Crystallography classification) or P6 3 mc (in Hermann–Mauguin notation). The Hermann-Mauguin symbols in P6 3 mc can be read as follows: [13] 6 3..
The body of the tables contain the characters in the respective irreducible representations for each respective symmetry operation, or set of symmetry operations. The symbol i used in the body of the table denotes the imaginary unit: i 2 = −1. Used in a column heading, it denotes the operation of inversion.
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.