Dear Students,
this has been great fun so far!
We like that you are asking so many questions on the forum and we enjoy all the photos you are uploading to our flickr page, for example the wonderful Escher-like tessellations by Daniel Wyllie:
https://www.flickr.com/photos/100542173@N05/14107072376/
Your fellow student @chemraven has some interesting posts about the symmetry of molecules on his blog:
http://chemdiary.blogspot.de/search/label/symmetry
Today, we will release Chapter 4 of our course.
We will focus on symmetry elements that separate crystal structures from macroscopic objects: glide planes and screw axes. For illustration purposes, the colorful locomotives appear again in some animations.
After that we are ready to climb up the the last step of our “ladder of crystal classification”, reaching, finally, the space groups. We will open the “crystallographers’ bible” and will explain what “psalms” are important to crystallographers.
After this week, we will take a short break. Some of you can catch up with the rest of the course. Others may want to review what they have learned so far. In the week after that we will take a close look at actual crystal structures. If you want to prepare yourself, you may already download and install the CCDC software “Mercury” on your computer. You can find it here:
http://www.ccdc.cam.ac.uk/Solutions/FreeSoftware/Pages/FreeMercury.aspx
Michael and Frank
PS:
You may also join our Crystal MOOC facebook page at:
https://www.facebook.com/crystalmooc
If you like, you can also share your location with your classmates, in order, for instance, to arrange local meet-ups:
https://www.zeemaps.com/map?group=780180
The Fascination of Crystals and Symmetry 