The important take-home message in this excellent article is surely the conclusion:
"The significant amount of programming effort and user frustration caused by the H3 and H32 space-group symbols is a good example of how time can be lost by not adopting long-established standards. This is not meant to suggest revising the PDB as this would certainly only serve to increase the confusion. Rather, it is a salient reminder to the entire crystallographic methods-developer community to avoid ad-hoc approaches whenever possible. Ever more automated systems require highly reliable components and unambiguous semantics. The effort spent early in ensuring reliability and clarity is usually rewarded many times over as time passes." ... and I would add adherence to established conventions. Cheers -- Ian On Wed, 22 Jul 2020 at 14:42, Gildea, Richard (DLSLtd,RAL,LSCI) < richard.gil...@diamond.ac.uk> wrote: > There is a useful article in Computational Crystallography Newsletter > 2011, 2, 12-14 that gives some background into the issues surrounding the > H3 and H32 symbols: > > "Fuzzy space group symbols: H3 and H32 > > http://www.phenix-online.org/newsletter/CCN_2011_01.pdf > > Cheers, > > Richard > > Dr Richard Gildea > Data Analysis Scientist > Tel: +441235 77 8078 > > Diamond Light Source Ltd. > Diamond House > Harwell Science & Innovation Campus > Didcot > Oxfordshire > OX11 0DE > ------------------------------ > *From:* CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of David > Vizarraga Revuelto <dvr...@ibmb.csic.es> > *Sent:* 22 July 2020 12:20 > *To:* CCP4BB@JISCMAIL.AC.UK <CCP4BB@JISCMAIL.AC.UK> > *Subject:* [ccp4bb] Question about P3, H3 and R3 space groups > > Dear all, > > Let me ask a question about the P3,H3, R3 space group annotations. > I had the idea that H3 was the recommended annotation for the hexagonal > representation of R3 (space group number 146). However, in the Birbeck > space groups web page (attached) H3 is associated with the space group > number 143 corresponding to P3. Similarly for all the other H groups > assigned in the page. Moreover in the web page none of the R space groups > is assigned to an H annotation. > > H3 corresponds to 143 or to 146? > Is there a space group 154 annotated as H32 1 2? > > Many thanks. > > > > "Note that the figure showing the relationship between primitive and > R-centred rhomohedral cells with hexagonal axes is clickable > > Rhombohedral with Hexagonal axes > 146. *R* 3 <http://img.chem.ucl.ac.uk/sgp/large/146bz1.htm> 148. *R* -3 > <http://img.chem.ucl.ac.uk/sgp/large/148bz1.htm> 155. *R* 3 2 > <http://img.chem.ucl.ac.uk/sgp/large/155bz1.htm> 160. *R* 3 *m* > <http://img.chem.ucl.ac.uk/sgp/large/160bz1.htm> 161. *R* 3 *c* > <http://img.chem.ucl.ac.uk/sgp/large/161bz1.htm> 166. *R* -3 *m* > <http://img.chem.ucl.ac.uk/sgp/large/166bz1.htm> > 167. *R* -3 *c* <http://img.chem.ucl.ac.uk/sgp/large/167bz1.htm> > H-centred Trigonal > 143. *H* 3 <http://img.chem.ucl.ac.uk/sgp/large/143bz1.htm> 144. *H* 31 > <http://img.chem.ucl.ac.uk/sgp/large/144bz1.htm> 145. *H* 32 > <http://img.chem.ucl.ac.uk/sgp/large/145bz1.htm> 147. *H* -3 > <http://img.chem.ucl.ac.uk/sgp/large/147bz1.htm> 149. *H* 3 2 1 > <http://img.chem.ucl.ac.uk/sgp/large/149bz1.htm> 150. *H* 3 1 2 > <http://img.chem.ucl.ac.uk/sgp/large/150bz1.htm> > 151. *H* 31 2 1 <http://img.chem.ucl.ac.uk/sgp/large/151bz1.htm> 152. *H* > 31 1 2 <http://img.chem.ucl.ac.uk/sgp/large/152bz1.htm> 153. *H* 32 2 1 > <http://img.chem.ucl.ac.uk/sgp/large/153bz1.htm> 154. *H* 32 1 2 > <http://img.chem.ucl.ac.uk/sgp/large/154bz1.htm> 156. *H* 3 1 *m* > <http://img.chem.ucl.ac.uk/sgp/large/156bz1.htm> 157. *H* 3 *m* 1 > <http://img.chem.ucl.ac.uk/sgp/large/157bz1.htm> > 158. *H* 3 1 *c* <http://img.chem.ucl.ac.uk/sgp/large/158bz1.htm> 159. *H* > 3 *c* 1 <http://img.chem.ucl.ac.uk/sgp/large/159bz1.htm> 162. *H* -3 *m* > 1 <http://img.chem.ucl.ac.uk/sgp/large/162bz1.htm> 163. *H* -3 *c* 1 > <http://img.chem.ucl.ac.uk/sgp/large/163cz1.htm> 164. *H* -3 1 *m* > <http://img.chem.ucl.ac.uk/sgp/large/164bz1.htm> 165. *H* -3 1 *c* > <http://img.chem.ucl.ac.uk/sgp/large/165cz1.htm> > > ------------------------------ > > 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 e-mail and any attachments may contain confidential, copyright and or > privileged material, and are for the use of the intended addressee only. 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Registered in England > and Wales with its registered office at Diamond House, Harwell Science and > Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom > > > ------------------------------ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > ######################################################################## 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/
