Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread Randy John Read
Hi Huw, When I was at the workshop, I have to admit that after ccp4i2 refused to do it I switched to Phenix and used phenix.reflection_file_converter! It would be better if i2’s reindex or change spacegroup task didn’t refuse, and I guess this might improve after the overly-zealous consistency

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread Huw Jenkins
Hi Randy, > On 23 Feb 2024, at 11:49, Randy John Read wrote: > > Why would we want to impose an arbitrary restriction on users for this > relatively common scenario. If the user has the unmerged data this can be imported into CCP4i2 via the data reduction task and merged in P1. How would you

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread Ian Tickle
On Fri, Feb 23, 2024 at 9:58 AM Winter, Graeme (DLSLtd,RAL,LSCI) < 6a19cead4548-dmarc-requ...@jiscmail.ac.uk> wrote: > While I get where you are coming from, it is still from a mathematical > standpoint correct to consider e.g. a tetragonal crystal as monoclinic - > P21 is a subgroup of

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread David Waterman
Hi Harry, I remember the C222/P622 confusion from some of Phil's old slides, and I thought that was an impressive case! It probably appears in a few places on the internet, but one I found just now is slide 15 of this presentation:

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread David Waterman
Hi Huw, This is tricky because in certain situations the cell parameter esds can get lost. For example if best_unit_cell= has been passed during scaling or merging with DIALS. Or, if cell parameter refinement was done using the LFBGS engine, in which case the esds are not calculated. Cheers

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread Randy John Read
In the recent crystallography workshop in Thailand, we had at least 3 cases brought by participants where we had reason to suspect that the data had been over-merged because of undetected twinning. Often there is more than one possible twinning operator and (as potentially in one of the cases

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread Huw Jenkins
> On 23 Feb 2024, at 09:58, Winter, Graeme (DLSLtd,RAL,LSCI) > <6a19cead4548-dmarc-requ...@jiscmail.ac.uk> wrote: > > so strictly it is possible and correct - if experimentally unlikely - to > have the situation we are discussing here occur. I believe this is only technically possible

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread Harry Powell
Hi Graeme (I may well have mentioned this when we shared an office) et al I’ll add something from my small-molecule crystallography days, when we used point detectors - so this would be pre-1996 which was the last time I used one of these machines. I don’t remember which structure it was (feel

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread Winter, Graeme (DLSLtd,RAL,LSCI)
Hi Huw (first: thank to Phil for picking this up; it caused much confusion) While I get where you are coming from, it is still from a mathematical standpoint correct to consider e.g. a tetragonal crystal as monoclinic - P21 is a subgroup of P43212 (say) so strictly it is possible and correct -

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-23 Thread Huw Jenkins
Hi Graeme, > On 21 Feb 2024, at 16:52, Winter, Graeme (DLSLtd,RAL,LSCI) > <6a19cead4548-dmarc-requ...@jiscmail.ac.uk> wrote: > > Processing a data set in lower than necessary symmetry e.g. tetragonal as > monoclinic you _cannot_ import the merged MTZ file into i2 because it is >

Re: [ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-21 Thread Phil Evans
That looks like an unnecessarily severe test buried in the i2 library, which maybe should just be a warning. I can probably have a look at it Phil Sent from my iPad > On 21 Feb 2024, at 16:52, Winter, Graeme (DLSLtd,RAL,LSCI) > <6a19cead4548-dmarc-requ...@jiscmail.ac.uk> wrote: > >  >

[ccp4bb] i2 won't accept 90 degree angles in moniclinic

2024-02-21 Thread Winter, Graeme (DLSLtd,RAL,LSCI)
Tried reporting to i2 dev list but it got bounced - feels like something others may hit so don’t feel _too_ bad sending to the bb with a tiny attachment [cid:CA3CE9EB-841D-41A3-A41E-F79714492B21] Hi Folks Helping someone out with some rather specialist data processing challenges and she hit