Space group type in Artemis
Hello, I have a question about the working of Artemis as a new user. Artemis does not recognize the space group B11b. When importing a cif file of a crystal with this symmetry, it sends a prompt message that the space group symbol cannot be recognized. As a result, I changed it to P11b and it works. But would this change any crystal information (for eg. Degen, Reff values) significantly? Thank you. Regards, Abhinav Prabhakar (Mr)
B11b in an alternate form of space group #9 (Cc or C1c1) Atoms does take Bb as the space group, but that could be Bb11 (which does not produce an error message) with unique x-axis instead of the unique z-axis in B11b. My suggestion: When I use a crystal structure in Atoms, I prefer to check the Inorganic Crystal Structure Database (ICSD) for a standard form of the structure (and a list of distances for comparision). That should net a structure in Cc format. Useful reference for space groups: http://img.chem.ucl.ac.uk/sgp/mainmenu.htm regards, -R. On 3/11/2017 2:56 AM, Abhinav Prabhakar wrote:
Hello,
I have a question about the working of Artemis as a new user.
Artemis does not recognize the space group B11b. When importing a cif file of a crystal with this symmetry, it sends a prompt message that the space group symbol cannot be recognized. As a result, I changed it to P11b and it works. But would this change any crystal information (for eg. Degen, Reff values) significantly?
Thank you.
Regards, Abhinav Prabhakar (Mr)
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On 03/11/2017 05:56 AM, Abhinav Prabhakar wrote:
Hello,
I have a question about the working of Artemis as a new user.
Artemis does not recognize the space group B11b. When importing a cif file of a crystal with this symmetry, it sends a prompt message that the space group symbol cannot be recognized. As a result, I changed it to P11b and it works. But would this change any crystal information (for eg. Degen, Reff values) significantly?
I am not a crystallography expert in any sense. When I wrote Artemis, I meticulously followed what I found in the fourth edition of the International Tables for Crystallography, Volume A. Every symbol defined in there is recognized by Artemis. (Well, I guess I should say that every symbol is /supposed to be/ recognized by Artemis. If one is missing, that's a bug and should be reported.) "B11b" is not a symbol that I found in my copy of ITC volume A. As Robert suggested, there may be a way to rotate group 9 so that "B11b" is an interpretable symbol in the abstract. But Artemis does not know how to do that. (Nor do I.) "P11b" is a setting for space group #7. If, as Robert suggests, your CIF file is for space group #9, then the answer to your last question is yes. It is plainly obvious that using a different space group will change the degeneracies and distances. Of course, you did not bother to include a copy of the CIF file in question to your original email, so it is not actually possible for Robert or I or anyone else to actually help you effectively. At the risk of sounding like an annoyingly broken record, everyone should take the time to ask a good question or write an actionable bug report: http://bruceravel.github.io/demeter/documents/SinglePage/help.html http://bruceravel.github.io/demeter/documents/SinglePage/bugs.html B -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 743, Room 114 Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/
participants (3)
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Abhinav Prabhakar -
Bruce Ravel -
Robert Gordon