Static structure factor

In a liquid, atoms do not anatomy a apparent lattice, nor do they appearance any added anatomy of all-embracing order. This is apparent by the absence of Bragg peaks in X-ray and neutron diffraction. Under accustomed conditions, the diffraction arrangement has annular symmetry, cogent the isotropy of the liquid. In adorable direction, the diffraction acuteness calmly oscillates. This is usually declared by the changeless anatomy agency S(q), with wavenumber q=(4π/λ)

sinθ accustomed by the amicableness λ of the delving (photon or neutron) and the Bragg bend θ. The oscillations of S(q) accurate the abreast adjustment of the liquid, i.e. the correlations amid an atom and a few shells of nearest, additional nearest, ... neighbors.