X-ray scattering from a discrete helix with cumulative angular and translational disorders.

X-ray scattering from a discrete helix possessing cumulative angular and translational disorders is studied by the Barakat model [Barakat (1987). Acta Cryst. A43, 45-49] assuming Gaussian distributions for random rotations and translations between subunits. This model is found to be identical to the paracrystalline model of the second kind. The intensity function shows that the intensity maximum decreases with increase in the Bessel order, whereas the peak breadth in the fiber direction and the intensity minimum increase.