Ichak rentgenografiyasi: natijani ko'rsatadigan tayyorgarlik

Deposition of the structure

Once the model of a molecule's structure has been finalized, it is often deposited in a crystallographic database kabi Kembrijning tarkibiy ma'lumotlar bazasi (for small molecules), the Inorganic Crystal Structure Database (ICSD) (for inorganic compounds) or the Protein ma'lumotlar banki (for protein and sometimes nucleic acids). Many structures obtained in private commercial ventures to crystallize medicinally relevant proteins are not deposited in public crystallographic databases.

Diffraction theory

Qo'shimcha ma'lumotlar: Difraksiyaning dinamik nazariyasi va Bragg difraksiyasi
The main goal of X-ray crystallography is to determine the density of electrons f(r) throughout the crystal, where r represents the three-dimensional position vektor within the crystal. To do this, X-ray scattering is used to collect data about its Fourier transform F(q), which is inverted mathematically to obtain the density defined in real space, using the formula
qaerda ajralmas is taken over all values of q. The three-dimensional real vector q represents a point in reciprocal space, that is, to a particular oscillation in the electron density as one moves in the direction in which q ochkolar. Uzunligi q ga mos keladi divided by the wavelength of the oscillation. The corresponding formula for a Fourier transform will be used below
qaerda ajralmas is summed over all possible values of the position vector r within the crystal.
The Fourier transform F(q) odatda a murakkab raqam, and therefore has a kattalik |F(q) | va a bosqich φ(q) related by the equation
The intensities of the reflections observed in X-ray diffraction give us the magnitudes |F(q) | but not the phases φ(q). To obtain the phases, full sets of reflections are collected with known alterations to the scattering, either by modulating the wavelength past a certain absorption edge or by adding strongly scattering (i.e., electron-dense) metal atoms such as simob. Combining the magnitudes and phases yields the full Fourier transform F(q), which may be inverted to obtain the electron density f(r).
Crystals are often idealized as being Mukammal periodic. In that ideal case, the atoms are positioned on a perfect lattice, the electron density is perfectly periodic, and the Fourier transform F(q) is zero except when q ga tegishli o'zaro panjara (so'zda Bragg cho'qqilari). In reality, however, crystals are not perfectly periodic; atoms vibrate about their mean position, and there may be disorder of various types, such as mozaika, dislokatsiyalar, har xil nuqsonli nuqsonlar, and heterogeneity in the conformation of crystallized molecules. Therefore, the Bragg peaks have a finite width and there may be significant diffuse scattering, a continuum of scattered X-rays that fall between the Bragg peaks.