Ind_X: program for indexing single-crystal diffraction patterns

Abstract

Indexing is an essential step in analysis of diffraction patterns. Diffraction of monochromatic radiation by a single crystal provides approximate positions of some nodes of the reciprocal lattice of the crystal, and the indexing problem lies in determining a lattice matching these positions. Ind_X is a program for indexing diffraction data given in the form of several approximate reciprocal lattice nodes. The applied method relies on testing potential volumes of the primitive cell of the reciprocal lattice. A subset of reciprocal lattice vectors supporting a given test volume is used to obtain tentative lattice bases. These are bases of low‐index superlattices of lattices based on triplets of supporting vectors. The Ind_X solution of the indexing problem consists of a list of best bases. The method turns out to be quite robust to data inaccuracies and spurious reflections. The program is relatively versatile, easily operated and freely accessible.

Indexing of grazing-incidence X-ray diffraction patterns: the case of fibre-textured thin films

“…Any other experimentally determined reciprocal-lattice vector has then to fit into this specific reciprocal lattice. Since complete three-dimensional vectors are used, even indexing of configurations with multiple lattices can be successfully achieved (Jacobson, 1976;Powell, 1999;Breiby et al, 2008;Gildea et al, 2014;Dejoie et al, 2015;Morawiec, 2017). In the case of powder diffraction, only the lengths of the reciprocal-space vectors are used and the unknown variables are then up to six unit-cell parameters (in the case of a triclinic system) and a set of Laue indices with a triple of three integer values each.…”

An efficient method for indexing grazing-incidence X-ray diffraction data of epitaxially grown thin films

“…We note that our method of combination of three reciprocal-lattice vectors has been suggested before (Duisenberg, 1992;Morawiec, 2017). In both cases this approach is used for solving difficult cases in single-crystal diffractometry such as twin lattices, fragmented crystals and unreliable data.…”

“…In the approach by Duisenberg, periodicities are sought by projecting all observed reciprocal-lattice vectors onto the normal to the plane given by three randomly selected points (Duisenberg, 1992 cases such as twin lattices, fragmented crystals and unreliable data. For such cases, Morawiec has developed another algorithm in which systematic combinations of three reciprocallattice vectors each are formed to search for periodicities of the calculated unit-cell volumes (Morawiec, 2017).…”

Constrained geometrical analysis of complete K-line patterns for calibrationless auto-indexing

“…Auto-indexing methods in general require precise reflection positions and as many reflections as possible. When considering Kossel line patterns that cover limited solid angles and contain only fractions of the lines, mostly of lower curvature, extraction of the scattering vectors of required quality and quantity is not straightforward (Henschel & Bauch, 2013;Enghardt & Bauch, 2015;Morawiec, 2016Morawiec, , 2017Heckert et al, 2018). Here we describe a complete procedure that allows indexing of Kossel line patterns in the crystallographic sense, i.e.…”