The
Cambridge Structural Database (CSD), is a repository for small
moleculeA molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
crystal structures. Scientists use single-crystal
x-ray crystallographyX-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...
to determine the crystal structure of a compound. Once the structure is solved, information about the structure is saved in a file (
CIF formatCrystallographic Information File is a standard text file format for representing crystallographic information, promulgated by the International Union of Crystallography . CIF was developed by the IUCr Working Party on Crystallographic Information in an effort sponsored by the IUCr Commission on...
) and deposited in the CSD. Other scientists can search and retrieve structures from the database.
The information consists of the
space groupIn mathematics and geometry, a space group is a symmetry group, usually for three dimensions, that divides space into discrete repeatable domains.In three dimensions, there are 219 unique types, or counted as 230 if chiral copies are considered distinct...
symmetry of the crystalline phase, its
cell parameterThe lattice constant [or lattice parameter] refers to the constant distance between unit cells in a crystal lattice. Lattices in three dimensions generally have three lattice constants, referred to as a, b, and c. However, in the special case of cubic crystal structures, all of the constants are...
s, the relative atomic coordinates of all the atoms in the cell in 3D.
Scientists can use the CSD to compare existing data with that obtained from crystals grown in their laboratories. The information can also be used to visualize the structure in a variety of software such as
atoms,
powdercell etc.
It is also possible to calculate what the theoretical
powder diffractionPowder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials.-Explanation:...
pattern of the phase would look like. This option is particularly important for analytical reasons because it facilitates the identification of phases present in a crystalline powder mixture without the need for growing crystals.
The CSD is compiled and maintained by the
Cambridge Crystallographic Data CentreThe Cambridge Crystallographic Data Centre is a crystallographic organisation based in Cambridge, England. It is a non-profit organisation whose primary role is the compilation and maintenance of the Cambridge Structural Database, a database of small molecule crystal structures...
.