Unit 5.2 - Ethylene - P21/n - Settings

[@anweshabera3640]

Just awesome explanation.......got a very clear view..... thanks a lot

[@ramon5734]

these videos are pure gold! Thank you for making this :)

[@FrankHoffmann1000]

Thank you very much for your kind comment!

[@manjuvvphysics7837]

Your video literally helped me a lot sir, I was searching for the procedure to transform from non-standard settings to standard of monoclinic which was raised to my final Ph.D. defense viva. This definitely helped me a lot. Thank you.

[@FrankHoffmann1000]

I think your recent question on twitter is now obsolete?

[@manjuvvphysics7837]

@@FrankHoffmann1000 Yes sir, I thank you very much.

[@jadetebogt1859]

Thank you so much for these videos, Frank 😃They have been so helpful. I struggled to grasp these concepts in my crystallography paper but have learnt so much from these short informative videos!

[@FrankHoffmann1000]

Welcome, I’m glad you like the videos

[@agb2557]

Thank you for you and your teams effort in making this publicly available. I am currently really interested in transformation matrices to convert from say, monoclinic or rhombohedral (hex) coordinates into a cubic orthonormal coordinate system. This will allow me to calculate the interatomic distances in supercells by simple Pythagorean calculations. So far I've been able to convert from a basis coordinate with non-equal cell lengths and 2 non-90 to the orthonormal basis, but can't seem to upgrade my matrix calculations to include the final 3rd angle so it can be a "universal" converter. I'm sure there is software for this, but it has definitely helped me understand matrix calculations better by doing this by hand. Is this something you plan on covering in the future? Or could you direct me to relevant literature? I've found the section (Part 5) in ITC vol A, though it is quite dense. Thanks again.

[@FrankHoffmann1000]

Hi, welcome! No, we are not planning such calculations in the future and I also do not know any relevant literature about this topic, sorry. If you do this manually this should be done by the usual Gram-Schmidt process, I guess. But there are indeed numerical difficulties in computer algorithms because of rounding errors. There are modified versions of it that prevent this errors. That's all I know about this topic. best wishes Frank

[@agb2557]

Frank Hoffmann actually I had not heard of the Gram-Schmidt process so thank you! I think this is exactly what I need.

[@FrankHoffmann1000]

@@agb2557 Perfect :-)

[@neopets25]

Hello Frank. Thank you for your work. Thank you also to Michael for his 3D animations that make things a hundred times easier to understand. I have two really simple questions if you do not mind: 1. Right from the get go, if we say that ethylene has a space group of P 1 21/n 1, it automatically means that its crystal class is monoclinic right? 2. Without using Mercury or any software, how do I know that an inversion symmetry element exists? I have to imagine the cell first? Thank you so much for your patience and time!

[@FrankHoffmann1000]

welcome 1) yes, P 1 21/n 1 belongs to the monoclinic crystal _system_ (not class), the crystal class is 2/m. 2) Unfortunaley, you can't get the information whether an center of inversion is present or not from the space group symbol - Mercury is one possibility, the other is, of course, to look at the International Tables for Crystallography. However, with increasing experience, one either knows whether the space group is centric or acentric, or at least develops a 'feel' for it 🙂 There are one and half website, where you can have a look at the space group diagrams: a) img.chem.ucl.ac.uk/sgp/large/sgp.htm (apparently down at the moment) and b) crystalsymmetry.wordpress.com/space-group-diagrams/

[@DiAoyUdAoprOtEctOr]

Perhaps someone knows how to change the style of packing? The displayed axes are so coarse that they completely wrap some of the inversion centers, which hinders the view. I know I could make the inversion center bigger. Just wondering if there is another option.

[@FrankHoffmann1000]

See 6.2.15 in this manual: www.ccdc.cam.ac.uk/support-and-resources/ccdcresources/mercury.pdf

[@Gorgeousbread11]

Hi Frank, many thanks for the sharing and really helpful lesson. I have a question: after the automotive had performed the screw operation, should it become upside-down?

[@FrankHoffmann1000]

Hi Gorgeousbread11, no, the motive doesn't change its orientation with respect to its horizontal mirror plane. best Frank

[@isotoxaltiling]

Dear Frank, thank you for your video. May i ask how the CIF file was generated? is the software mercury used to generate it or another software? Thanks.

[@FrankHoffmann1000]

Dear Mark, well, the visualization of the CIF was done with Mercury. However, the CIF itself is usually created during the solution and refinement of the crystal structure (usually by X-ray diffraction methods) with, for instance, Shelx. All crystal structures are then made available in certain databases, such as the CCDC (for organic organometallic and metal-organic structures) or ICSD (for inorganic compounds), where you can download these CIFs. best wishes Frank

[@中国加油-k3u]

Thanks for your sharing! What a rewarding video it is! In addition, can you systematically explain the R-3m space group and its-belonged LiCoO2, a popular cathode materials for lithium ions batteries. Its all SEs of diagram and correlation between this diagram and real atomic arrangement of LiCoO2 have confused me for a long time. Thank you very much

[@FrankHoffmann1000]

I am not able to do so at the moment. The most urgent task in these Corona virus times is to further digitize some lectures that I usually give in my classes at the University of Hamburg. Thank you for your understanding!

[@中国加油-k3u]

@@FrankHoffmann1000 em. Wishing you good health, and that everything goes well. Beat the virus as soon as possible for our world

[@FrankHoffmann1000]

Yes, let's do this! Hope you will stay healthy as well!

[@JuanGarcia-lo2el]

Dear Frannk, your videos are incredible awesome! Do you have more material to learn about ? I'm a theoretical chemistry postgraduate student and I'm very interested in the theorerical study of crystal structures!

[@FrankHoffmann1000]

Sorry Juan - KZbin had some problems with the notification function about comments, so I did miss your comment. Thanks very much for your kind words! Unfortunately, I don't have more learning materials right now.

[@bobukuttan]

Dear Frank, thanks for uploading this video. I have a doubt regarding how to download the mercury software. I went to the following website "www.ccdc.cam.ac.uk/support-and-resources/Downloads/". There are lot of options. Do we need to download everything or just the software mentioned as "Mercury 3.10 Windows"

[@FrankHoffmann1000]

Dear Bobu Manuel, just Mercury 3.10 Windows is sufficient! best regards Frank

[@bobukuttan]

Thanks Frank, i have downloaded the same