Скачать или смотреть Unit 4.4 - Screw Axes in Crystal Structures

Unit 4.4. of our course The Fascination of Crystals and Symmetry

Additonal resources at: https://crystalsymmetry.wordpress.com...

In this unit we want to investigate, what different kinds of screw axes, that is, what kind of different helical symmetries are present in crystal structures.

Possible screw axes are: two-one, three-one, four-one, four-two, six-one, six-two, and six-three.

In addition there are these enantiomorphous axes, this means mirror images of already mentioned axes, namely, three-two, which is the enantiomorphous screw axis of three-one, four-three is the screw axis with opposite handedness of four-one, and six-four and six-five are the enantiomorphous screw axes of six-two, and six-one, respectively.

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