Chirality Induction The Adam Effect

Twofold improper rotation axis (.Sj) rotation followed by mirror rcncciton 

To make matters even more complicated, it is much more convenient in crystallography to use an entirely different system of symmetry symbols, termed the Herman-Maugin (as opposed to Schoenflies) notation (Table 8.2). 

Combining the five point group symmetry operators with the two translational symmetry operators gives a total of exactly 230 different possible combinations, called the crystallographic space groups. Every crystal 

Screw axis (180° rotation followed by translation by of the unit cell length parallel to the rotation axis, e.g. 2i 180° rotation plus a half cell translation) 

Glide plane a, b, c, n, d (reflection + translation a half cell in indicated direction, e.g. a is a translation in the x direction) 

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