Dear Marina, Just to add a couple of points, if you're using a Bruker machine, the programs RLATT can help visualize problem reflections; CELL_NOW is another program that can help. I found XDS to be useful in integration in such cases.
You might also like to check out Regine Herbst-Irmer's article "Twinning in chemical crystallography – a practical guide" (2016) <https://www.degruyter.com/document/doi/10.1515/zkri-2016-1947/html>. Best wishes, Navdeep https://scholar.google.de/citations?user=ZqU1AE0AAAAJ --- On 12.03.21 14:11, Schreuder, Herman /DE wrote: > Dear Marina, > > A lot can happen with twinning andthe crystallization process does not always > adhere to rules written in text books. > The first thing I would do is to look at the predicted spots to see if the > "split" spots are predicted as single spots (and would then really be split), > or if they are predicted as two different spots (and would therefore not be > split). > I assume that the cell dimensions of the P622 and P3(2)21 cell are the same > (no doubling of some sell axis) and that the detection of twinning was based > on the intensity distribution of the data set. > What may have happened is that if the transition between the two twin domains > is not perfect, the two twin domains may have slightly different > orientations, leading to split spots. > > My 2 cents, > Herman > > -----Ursprüngliche Nachricht----- > Von: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> Im Auftrag von Marina > Gárdonyi > Gesendet: Freitag, 12. März 2021 11:31 > An: CCP4BB@JISCMAIL.AC.UK > Betreff: [ccp4bb] Can twinning be seen in the diffraction pattern? > > > Hello everyone, > > I am a PhD student at the Philipps-University in Marburg and I am currently > writing my thesis. > > I have problems to understand whether in my case twinning can be seen in the > diffraction pattern or not. > > I know that it depends on the type of twinning wheter you can see it in the > diffraction pattern. The crystal had a resolution of 2.2 A. > During processing it seemed to have the space group P622, but in the end it > was P3(2)21. With phenix Xtriage I found out, that the data set was twinned. > The twin law was -h,-k,l. So it should be merohedral twinning. > I read in a paper, that in case of merohedral twinning you cannot see it in > the diffraction pattern. But in my case that seemed not to be the case > because of splitted reflections. Or am I wrong??? > > I would be very happy to hear your opinion on that. Thanks in advance! > > Best regards, > Marina > > -- > Marina Gárdonyi > > PhD Student, Research Group Professor Dr. Klebe > > Department of Pharmaceutical Chemistry > > Philipps-University Marburg > > Marbacher Weg 6, 35032 Marburg, Germany > > Phone: +49 6421 28 21392 > > E-Mail: marina....@pharmazie.uni-marburg.de > > https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.agklebe.de%2F&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=lcvs%2Fk2xR0IsD0jw4VTEU25lfReTwByxq9ci%2F%2Bn9b1U%3D&reserved=0 > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jiscmail.ac.uk%2Fcgi-bin%2FWA-JISC.exe%3FSUBED1%3DCCP4BB%26A%3D1&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=A%2F9uSyur0W1vC%2BsKwSQtMVwo145vctPNXkXjQrrQPBo%3D&reserved=0 > > This message was issued to members of > https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.jiscmail.ac.uk%2FCCP4BB&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=Qied8%2BDj6d46h1p8Y%2BNK%2F7gIIv9iDxT2%2Fjd3dM7llQE%3D&reserved=0, > a mailing list hosted by > https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.jiscmail.ac.uk%2F&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=uRUeCZQHZlWS0iGJrBYSmyulHDMHayMsb1wCxcYeuwA%3D&reserved=0, > terms & conditions are available at > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.jiscmail.ac.uk%2Fpolicyandsecurity%2F&data=04%7C01%7CHerman.Schreuder%40SANOFI.COM%7C0e4183749baa4f9ab10308d8e541e581%7Caca3c8d6aa714e1aa10e03572fc58c0b%7C0%7C0%7C637511419204410172%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=AFsBVc5LtTklf4gzMCItFESgyTCuwqLLZk77ypDYEcE%3D&reserved=0 > > ######################################################################## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing > list hosted by www.jiscmail.ac.uk, terms & conditions are available at > https://www.jiscmail.ac.uk/policyandsecurity/ > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
