 |
 |
Dear Crystallographers, In detwinning a dataset, I noticed that correction of the intensity distributions works dramatically better for the acentric versus centric (see attached plots). In this case it is P3212 and the twin operator is (-h,-k,l). Can anyone suggest why this might be the case? Should the algorithm be different for centrics than for acentrics (I can't see why...)? All the best, Jacob Keller PS: btw, I came across an interesting phenomenon in this spacegroup which experienced crystallographers no doubt will be aware of, but just felt it amusing enough to share. When there is a non-orthogonal axis, HKL's of seemingly-different resolution can be the same resolution. For example, in this spacegroup, the two reflections (3,2,4) and (-5,3,4) are equivalent reflections and are of the exact same resolution. This is because when one "walks down" the H axis in reciprocal space 3 units and up 2 units in K, the walk up K takes you *farther* from the origin due to the 60 deg angle between K and H. Conversely, when one walks down H -5 units, then up 3 units, the 3 units in K bring you *closer* to the origin, again due to the tilt of K with respect to H. I thought this might be interesting to somebody out there. ******************************************* Jacob Pearson Keller, PhD Looger Lab/HHMI Janelia Research Campus 19700 Helix Dr, Ashburn, VA 20147 email: [log in to unmask] *******************************************