X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

, crystallographic disorder describes the

cocrystal In materials science (specifically crystallography), cocrystals are "solids that are crystalline, single- phase materials composed of two or more different molecular or ionic compounds generally in a stoichiometric ratio which are neither solva ...

lization of more than one

rotamer In chemistry, rotamers are chemical species that differ from one another primarily due to rotations about one or more single bonds. Various arrangements of atoms in a molecule that differ by rotation about single bonds can also be referred to as ...

conformer A conformer is a clear acrylic shell fitted after an enucleation of the eye Enucleation is the removal of the eye that leaves the eye muscles and remaining orbital contents intact. This type of ocular surgery is indicated for a number of oc ...

, or

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...

where the

center of mass In physics, the center of mass of a distribution of mass in space (sometimes referred to as the barycenter or balance point) is the unique point at any given time where the weight function, weighted relative position (vector), position of the d ...

of each form is identical or unresolvable. Due to disorder, the crystallographic solution is the sum of the various forms. In many cases, the components of the disorder are equally abundant, and, in other cases, the weighting coefficients for each component differ. Disorder can entail a pair or several components, and usually arises when the forms are nearly equal in

energy Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...

and the

crystal lattice In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystal, crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that ...

is sufficiently spacious to accommodate the various components. File:DOSBIW.png, Structure of pentamethylmolybdenum, , showing 4-fold disorder of one

methyl group In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated a ...

. File:DOSBIWoneRotamer.png, One of four rotamers of .

References

Crystallography Materials science Protein structure Protein methods Protein imaging Synchrotron-related techniques {{crystallography-stub