Dear 'old' crystallographers,
During one case of structure solution, the data processing programs output
incorrect space group-primitive cubic P4132, which later found out that the
correct one should be face centerd cubic f23. This problem was caused by
perfect twinning.
Now I'd like to invite you to help me understand, and explain in details,
WHY, IN CASE OF PERFECT TWINNING, THE LAUE GROUP m-3 WILL BE MIS-INDEXED TO
m-3m by some data processing programs? I, sort of, understand the reason behind
this is caused by the perfect twin operator which will emulate an additional
2-fold axis. But not fully understand the symmetry in details in this case.
Your help and teaching are highly appreciated.
Yanming Zhang
