Dear community members, I recently received a different opinion regarding whether one sample should be C121 or I121.
I am trying to integrate automatic data processing and displaying resutls to users. In the pipeline, I run pointless to get the best space group solution, in the end of this message comes the detailed pointless output related to space group determination that I got for one of the samples. I took the best solution from pointless, i.e. I121 (Cell: 81.74 67.10 86.75 90.00 98.20 90.00). However, I later also extracted the space group and unit cell result from the phenix.xtriage output and got C121 (Cell: 110.377 67.1 81.744 90 128.931 90). The space group number indicates space group 5 from both cases, and according to the International Tables for Crystallography Volume A: Space-group symmetry Second online edition (2016) [ISBN: 978-0-470-97423-0 (https://it.iucr.org/services/purchase/)[doi: 10.1107/97809553602060000114](http://dx.doi.org/10.1107/97809553602060000114), space group 5 should be C121. Could I receive some wisdom from the community regarding whether one is correct, and if so, which one, or whether both are correct? Any further comments/opinion regarding whether I should display both options (I121 and C121 with their corresponding unit cell parameters) would be helpful. Thank you so much in advance! Best, Dawn pointless output: <!--SUMMARY_BEGIN--> Input file is merged so subgroups of the input symmetry are omitted Only groups of the same or higher symmetry are kept WARNING: very low completeness 0.38 in merged file, may not be able to determine Laue group Laue Group Lklhd NetZc Zc+ Zc- CC CC- Rmeas R- Delta ReindexOperator = 1 I 1 2/m 1 *** 1.000 8.53 8.53 0.00 0.85 0.00 0.07 0.00 0.0 [-l,k,h+l] <!--SUMMARY_END--> ******************************************************** Testing Lauegroups for systematic absences ------------------------------------------ No systematic absence zones to test in this lattice group Time for systematic absence tests: 0.053 secs Possible spacegroups: -------------------- Indistinguishable space groups are grouped together on successive lines 'Reindex' is the operator to convert from the input hklin frame to the standard spacegroup frame. 'TotProb' is a total probability estimate (unnormalised) 'SysAbsProb' is an estimate of the probability of the space group based on the observed systematic absences. 'Conditions' are the reflection conditions (absences) Spacegroup TotProb SysAbsProb Reindex Conditions I 1 2 1 ( 5) 1.000 1.000 [-l,k,h+l] --------------------------------------------------------------- Space group confidence (= Sqrt(Score * (Score - NextBestScore))) = 1.00 Laue group confidence (= Sqrt(Score * (Score - NextBestScore))) = 1.00 Selecting space group I 1 2 1 as there is a single space group with the highest score <!--SUMMARY_BEGIN--> $TEXT:Result: $$ $$ Best Solution: space group I 1 2 1 Reindex operator: [-l,k,h+l] Laue group probability: 1.000 Systematic absence probability: 1.000 Total probability: 1.000 Space group confidence: 1.000 Laue group confidence 1.000 Unit cell: 81.74 67.10 86.75 90.00 98.20 90.00 $$ <!--SUMMARY_END--> HKLIN spacegroup: C 1 2 1 C-centred monoclinic The input crystal system is C-centred monoclinic (Cell: 110.38 67.10 81.74 90.00 128.93 90.00) The crystal system chosen for output is body-centred monoclinic (Cell: 81.74 67.10 86.75 90.00 98.20 90.00) ######################################################################## 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/
