Automatic indexing of rotation diffraction patterns

TLDR

The method assumes known space group and approximate unit‑cell parameters. The study presents a method for assigning indices to single‑crystal reflections from rotation‑oscillation data, tolerating large initial errors. Orientation is determined from diffraction patterns of one or more oscillation records, and parameters are refined to satisfy space‑group symmetry constraints.

Abstract

A method is described which assigns indices to a set of single-crystal reflections recorded by the rotation-oscillation technique using a fixed X-ray wavelength. It is assumed that the space group and approximate unit-cell parameters are known. The unknown crystal orientation is determined directly from the observed diffraction pattern of one or several oscillation data records. A local indexing procedure is described which tolerates large initial errors in the parameters controlling the diffraction pattern. These parameters are refined subsequently, thereby satisfying the constraints imposed by the space-group symmetry.