Round robin on structure analysis from 3D electron diffraction data

3D electron diffraction (3D ED) has undergone impressive development in the last decade. However, its accuracy and reproducibility have never been tested, up to now, in different laboratories on the same batch of samples. This paper reports a round robin on three test structures, two inorganic and one organic, solved and refined with 3D ED in seven different laboratories employing different transmission electron microscopes, with different acceleration voltages, different methodologies and different detectors. The results of the round robin show a remarkable accuracy of the technique that, in the case of kinematical refinement, is around 0.05 Å error on atomic positions for the inorganic samples and 0.15 Å for the beam-sensitive organic crystal. Dynamical refinement further improves the accuracy. The analysis of diverse samples and numerous data sets again confirms that dynamical refinement is a well established procedure, significantly reducing the refinement R factors, improving the accuracy of the structure models in most cases, and providing fine structural details, such as hydrogen-atom positions and the absolute structure, for both inorganic and organic samples.