International Union of Crystallography
Encyclopedia
The International Union of Crystallography (IUCr) is a member of the International Council for Science (ICSU)
International Council for Science
The International Council for Science , formerly the International Council of Scientific Unions, was founded in 1931 as an international non-governmental organization devoted to international co-operation in the advancement of science...

and exists to serve the world community of crystallographers.

It was founded 1948 with the help of Ralph Walter Graystone Wyckoff
Ralph Walter Graystone Wyckoff
Ralph Walter Graystone Wyckoff, Sr. was an American scientist and pioneer of X-ray crystallography. He was elected Foreign member of the Royal Society, on April 19, 1951....

who served as Vice-president and President from 1951 to 1957.

Symmetry notation

The IUC notation is the notation for the symmetry group adopted by the International Union of Crystallography in 1952. It names the wallpaper group
Wallpaper group
A wallpaper group is a mathematical classification of a two-dimensional repetitive pattern, based on the symmetries in the pattern. Such patterns occur frequently in architecture and decorative art...

s with a 4 character name. First it has a P or C for primitive or centered groups. Groups are given a number 1, 2, 3, 4, or 6 for the highest order of symmetry. Groups can have one or two reflections, given as vertical mirrors first (horizontal reflection), and horizontal second (vertical reflection). A simple reflection is given an m (mirror), and a glide-reflection is given a g. Place holder 1 are given for an orthogonal direction with no reflections.

• X-ray crystallography
X-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...

• Crystallography
Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...

• Open Access Scholarly Publishers Association
Open Access Scholarly Publishers Association
The Open Access Scholarly Publishers Association is an industry association which aims to promote open access publishing and to establish best practices in the field...

, of which IUCr is a member