I am trying to understand the symmetry elements of space group number 194 (P$6_3$/mmc), which is hexagonal and has 24 symmetry operations.

In the table of symmetry operations it says that it has three glide planes, which I marked in the figure (see blue rectangles). However, more than three glide planes are represented in the figure, since there are more dashed, dashed-dotted and dotted lines than those lines which are represented in the rectangles. Why do more glide planes appear than those three on the table of symmetry operations?

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(Images taken from International Tables of Crystallography)

  • 1
    $\begingroup$ Have you checked if the directions at 120 or 60 degrees to each other are distinct? It is possible that the three highlighted glide planes are equivalent due to hexagonal symmetry. $\endgroup$
    – Mythreyi
    Aug 31, 2020 at 14:09
  • $\begingroup$ Hi Carmen, have you had time to try to answer @Mythreyi's question? $\endgroup$ Nov 29, 2020 at 3:52


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