Figure 3
Cumulative intensity distribution curves for a DAOCS crystal with a twin fraction of 0.32, produced with TRUNCATE (Collaborative Computational Project, Number 4, 1994). In the graph N(z) is plotted as a function of z, in which z = I/〈I〉 and N(z) is the fraction of the reflections whose intensities are less than or equal to z (Howells et al., 1950). The dashed line shows the theoretical distribution for centric reflections and the grey line that for non-centric reflections. The black line shows the observed distribution for non-centric reflections. Since for twinned crystals observed intensities consist of two (or more) components, there will be fewer observations with extremely low intensity, which results in a sigmoid cumulative intensity distribution curve. |