UnwarpCalculator: a utility to estimate intensity distribution in reciprocal space for an arbitrary 3D set of atoms

Abstract

UnwarpCalculator is a command-line utility developed to calculate intensity distribution in reciprocal space. The program uses CIF syntax input files and can work either with periodic crystals or with arbitrary atomic distribution, including incommensurately modulated and defect structures. With this program the intensity can be calculated for any reciprocal space point using the three main options available, including intensity calculation at a point with (h, k, l) coordinates, intensity distribution calculation along a line in reciprocal space and building an unwarped layer pixel by pixel. The program has an interactive interface and uses a fairly simple diffraction calculation model. The tool can be used for teaching crystallography since it offers much easier options and input file creation compared with existing software for defect and diffraction pattern simulations. These features along with input files with CIF syntax allow easy use of the program even for beginners. The utility can also be applied for the interpretation of experimental diffraction patterns and comparison of calculated versus experimental diffraction images to validate crystal structure models.