For cases where people have had merohedral twinning, did the twin fraction vary substantially between individual crystals grown under indentical conditions? I have no prior experience with merohedral twinning, and was surprised to see that the twin fraction varied substantially as detailed below, and that by screening we were able to get untwinned xtals.
The project started with a weak home data set for which the twin fraction was 0.478, and which scaled in both H3 and H32. We just came back from APS with data sets from another three crystals, for which the ML twin fraction, estimated using phenix.xtriage with scalepack merged intensities as input, varied from 0.335, 0.219 and 0.02. The latter is refining very nicely, in H3 and will not scale in H32. Thanks - Mark
