Comparison of observed and calculated diffraction patterns for both forms (I) and (II) of paracetamol. In all figures the upper and lower half-circles represent the observed and calculated diffuse diffraction patterns for a basal section of reciprocal space. (a), (b) and (c) are respectively the h0l, hk0 and 0kl basal sections for form (I) and (d), (e) and (f) are the same sections for form (II). The direction of the reciprocal axis also corresponds to the packing diagrams in Fig. 1. Observed and calculated images have a scaling and background correction applied as required. Bragg peaks are omitted from the calculated images. Diffraction sections are calculated from models in which the parameters corresponding to equation (2) were refined using the automated least-squares procedure described in §2.4. The number of MC cycles used for each simulation during the automated refinement is 1000, however, for the images shown 10 000 cycles are used to reproduce sharper diffraction features.