Flack parameter reporting enquiry

[Natalie Johnson]

Dear all,



I was also contacted by David Watkin about the flack parameter and have some statistics on the presence of some of the absolute structure fields in CIFs in the CSD.



I have extracted the number of CIFs where particular fields are included (for structures in CSD up to October 2019 where has a CIF - approximately 750,000) (table attached to this email).



I am currently looking at the content of some of these fields to assess if it is possible to identify the type of parameter (flack, hooft, parsons etc.) from information in the _refine_ls_abs_structure_details field. It is looking like a number of different parameters are being reported in the _refine_ls_abs_structure_Flack field (and there are cases where another parameter is reported in that field too e.g. a value for hooft).



I have had a brief look at the Rogers field and approximately 180 of the 1834 CIFs which include the Rogers field have a numerical value in the field. There are very small number of CIFs (~10) including this parameter from papers published in the last few years.



Best wishes,



Natalie


From: coreDMG <coredmg-bounces at iucr.org> On Behalf Of Spek, A.L. (Ton) via coreDMG
Sent: 21 July 2020 13:42
To: Mike Hoyland via coreDMG <coredmg at iucr.org>
Cc: Spek, A.L. (Ton) <A.L.Spek at uu.nl>
Subject: Re: Flack parameter reporting enquiry

All,

This is indeed a longstanding issue.
With SHELXL, the CIF dataname 'Flack' is 'overloaded' with its real source (i.e. refined and applied, or post-refinement and not applied) to be gleaned from text items (e.g. the embedded .ins file and 'details' text)

I think that the Rogers parameter can be retired.

Best wishes

Ton

Prof. dr. A.L.Spek (Emeritus)
Utrecht University
Bijvoet Center for Biomolecular Research
Padualaan 8
3584 CH, Utrecht
The Netherlands

E-mail:a.l.spek at uu.nl
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________________________________
Van: coreDMG <coredmg-bounces at iucr.org<mailto:coredmg-bounces at iucr.org>> namens Brian McMahon via coreDMG <coredmg at iucr.org<mailto:coredmg at iucr.org>>
Verzonden: dinsdag 21 juli 2020 13:28
Aan: Mike Hoyland via coreDMG <coredmg at iucr.org<mailto:coredmg at iucr.org>>
CC: Brian McMahon <bm at iucr.org<mailto:bm at iucr.org>>
Onderwerp: Re: Flack parameter reporting enquiry

Mike

Thanks for sending this - my "to do" list isn't getting anywhere very
fast at the moment.

Brian

On 21/07/2020 12:00, Mike Hoyland via coreDMG wrote:
> Dear All,
>
> We have had the following correspondence regarding the reporting of Flack
> parameters which we thought would be good to be discussed in this forum. It
> was sent to us by David Watkin.
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Natalie Johnson
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