XD1DD

The computer program is designed to calculate powder X-ray diffraction patterns for one-dimensionally (1D) disordered crystals, i.e. containing planar defects. Calculations are made on the basis of statistical models, where the Markov chain with stationary transition probabilities is used as a probabilistic rule for generating a 1D disordered sequence of layers. The model takes into account the short-range order in the alternation and methods of layer superposition, which allows simulating various cases of distribution of planar defects in crystals. To obtain a powder diffraction pattern, calculations are carried out in three-dimensional reciprocal space along rods passing through the nodes of the reciprocal two-dimensional lattice. The program allows one to determine the type and estimate the concentration of planar defects of the studied sample particles by creating a model of a 1D disordered crystal and optimizing it by trial and error until the best match with the experiment.