> - The matrices representing the space-group operators are no longer > diagonal, and the distinction between R*h and h*R (where R is the > rotation matrix and h is the reciprocal space vector [h,k,l]) becomes > important when calculating systematic absences. This does make sense. Many of the programs draw the structure properly so get the symmetry elements right - the trouble is elsewhere.
>And as a third possible source of error, I have noticed that trigonal >space groups lead to a rounding error in the translational part that is >different from other space groups. Which would make sense if e.g. the >program internally defines the translational components of the symmetry >operators as 0.3333 instead of 1.0/3.0 (not: 1/3). This would also crop up in quartz, where the Si z coordinate is 2/3. If you shift it the multiplicity goes from 3 to 6. Pam
