Gert
Many, many years ago I worked in Rossmann's lab. Some colleagues were
detwinning a structure. Whatever they tried, the twin ration went from
something near 50-50 to something near 95-5 without any improvement. I
wrote software that would look at reflection files in search of
systematic absences (don't laugh these were the days before the
internet; we still used puched cards) and corrected their spacegroup
from P23 to P213 (or something similat; at least a sub-1 was added).
That saved that day. So my only X-ray experience gave one example where
detwinning doesn't work: wrong spacegroup.
