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Re: [ccp4bb] refinment in lower space group vs. higher |
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CCP4bb navigationCCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999Subject: Re: refinment in lower space group vs. higher From: Anastassis Perrakis a {- dot -} perrakis {- at -} NKI {- dot -} NL Date: 2009-01-03 Also try BALBES from the York site supplying the high symmetry data and let it check things for you. Sent from my iPhone On 3 Jan 2009, at 14:40, James Holton > You should pick your free-R set in C2221 and then symmetry-expand it > to C2. Otherwise, every hkl in your "free" R set will have an NCS > "mate" in the working set, and using NCS restrains will completely > invalidate the free R analysis. That is, your free-R will be > essentially equal to the regular crystallographic R and it will be > possible to take a completely wrong MR solution and refine it to an > "acceptable" free R, and if you do that, we will all make fun of you. > > -James Holton > MAD Scientist > > Yu Jiang wrote: >> >> Dear all, >> >> I am now refining one structure in space group C2 with 2 molecules, >> however we find the data can be processed in C2221 with 1 molecule. >> The questions are: >> >> 1. Can I still use space group C2 instead of C2221, even if the two >> molecules almost have crystallographic symmetry? Should I provide >> any excuses? >> >> 2. Is there any indication or necessity to refine structures in >> lower space group instead of higher? >> >> Many thanks! >> >> CCP4bb navigationCCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999 |
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