Automated determination of the extinction symbol via electron diffraction data

The identification of the extinction symbol is routine for single-crystal X-ray data. Because of peak overlap and possible preferred orientation the task is more difficult for powder diffraction data, but recent computer programs based on probabilistic approaches have made it more automatic. This paper describes a new algorithm for the automatic identification of the Laue group and of the extinction symbol from electron diffraction intensities. The algorithm has a statistical basis and tries to deal with the severe problems arising from the often nonkinematical nature of the diffraction intensities and from the limited accuracy of the lattice parameters determined via electron diffraction. The approach has been checked using a wide set of test structures.