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Figure 2
Illustration of Criterion 2[link] with simulated CBED patterns from alpha-quartz (space group P3121) near [[\bar 1 \bar 3 \bar 7]] at 200 kV. Condition I is satsified in (a) but not in (b). The yellow lines label the width of the first bright fringe relative to the second one. Condition II is satisfied in (c) but not in (d). The intensity profiles along the dashed red arrows in (c) and (d) are shown in (e) and (f), respectively. In the calculation of (c) and (d), the same set of parameters as those in the calculation of (a) and (b) were used except that the coupling structure factor, [{V_{{\bf{h}} - {\bf{g}}}}], was artifically increased to produce a strong coupling case of three-beam diffraction as opposed to the weak/moderate coupling case in (a) and (b).

IUCrJ
Volume 5| Part 6| November 2018| Pages 753-764
ISSN: 2052-2525
https://doi.org/10.1107/S2052252518012216