Chemical Forums
Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: Ticklezpanda on April 16, 2016, 01:48:51 PM
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Hello everyone,
I am studying for my final exam for Solid State Chemistry and I can't seem to visualize Screw Axes and Glide planes properly. For example, for question one on the attached picture I draw a 2D crystallographic plane (b,c plane). Now the Screw Axis is at (x,1/4,0) which is probably the thing that confuses me the most. I know that a 2,1 screw axis is a rotation of 180 degrees and a translation of 0.5 along the axes in which the rotation occurs.
What confuses me is the visualization of such a screw axis. How is a screw axis (which is an operation) located at a specific point on the plane? The way I visualize it is a screw axis from the atom pointing in the x direction (a) so you obviously add 0.5 to x. Also if there is a 180 degree rotation from the atom y and z should be negative. I'm not really sure how to visualize the rest of the problem.
Any guidance is graciously appreciated.