XIDENT : a computer technique for the direct indexing of electron diffraction spot patterns

摘要

A rapid computer technique to index electron diffraction spot patternsfrom any crystal structure is described. The diffracting zone, whichis represented to the computer by the measured diffracted distances ofthree or five diffraction spots and the angles between them, is comparedwith the reciprocal lattices of phases likely to be present, and allzones which correspond within prescribed limits are printed out in orderof best fit. The program provides for automatic rejection of prohibitedreflections for the Bravais lattices, and for the suppression ofsymmetrical solutions if desired. The technique is of general application,but has proved particularly useful for the indexing of patterns fromunidentified non-cubic structures in situations where experimental errormust be tolerated.