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Re: What does it mean for _diffrn_ambient_temperature and_cell_measurement_temperature to be different?
- To: "Spek, A.L. (Ton)" <A.L.Spek@uu.nl>
- Subject: Re: What does it mean for _diffrn_ambient_temperature and_cell_measurement_temperature to be different?
- From: James H via coreDMG <coredmg@iucr.org>
- Date: Mon, 24 Jan 2022 13:02:40 +1100
- Cc: James H <jamesrhester@gmail.com>, Distribution list of the IUCr COMCIFS Core Dictionary Maintenance Group<coredmg@iucr.org>
- In-Reply-To: <F3E75B99-D8C4-4CD8-B09D-324FB1FA50A9@uu.nl>
- References: <CAM+dB2cv9Q2FGVrwKNfJc-NqbSbKYK+uxsHnj+txw65ECEXGAQ@mail.gmail.com><F3E75B99-D8C4-4CD8-B09D-324FB1FA50A9@uu.nl>
Thank you all for your insights and information. I think the best way forward is simply to clarify in the definitionsthat the cell_measurement_temp/pressure items would only differ(slightly) from _diffrn_ambient_temp/pressure where the cell wasdetermined separately from the diffraction pattern. If these items areabsent their default values can be taken from the corresponding_diffrn_ambient items. Making the reverse deduction can be a matter ofpolicy for CIF curators. If there are no objections, I will make the updates to the coredictionary. You can follow along and comment here:https://github.com/COMCIFS/cif_core/issues/294 On Tue, 18 Jan 2022 at 20:19, Spek, A.L. (Ton) <A.L.Spek@uu.nl> wrote:>> James,> A good point.> IUCr/PLATON/checkCIF sends out an A-level ALERT for this. Referees should have picked this up.> Older SHELXL versions put in a default value for those values in the CIF they generated (Room Temperature)> A quick check of the CIF's for all structures published in the 2021 issues of Acta Cryst. E77 shows that there are no inconsistencies there.>> Best wishes>> Ton>>> Op 18-01-2022 06:47 heeft coreDMG namens James H via coreDMG <coredmg-bounces@iucr.org namens coredmg@iucr.org> geschreven:>> Happy New Year everybody.>> Here is our first issue for the year:>> At first glance it would appear to me that _diffrn_ambient_temperature and> _cell_measurement_temperature are describing the same thing. There may> have been a difference in the past when using point detectors and the> cell was determined separately to the data collection, but for> anything collected on an area detector I would have expected these> values to be the same. However, I've noticed from looking at around> 10000 files from the COD that, of the files that have both data names,> around 1% have different numbers. I'm wondering what this could> possibly mean, especially when the two numbers are very different e.g.> 150K and 296K. Given that the cell parameters are necessary to obtain> absolute distances from fractional coordinates, if the diffraction> data are collected at a different temperature to the cell measurement,> then surely these atomic distances would be incorrect? How do the> database curators handle this? How are software authors interpreting> these two data names for output or input?>> If you agree that there is no way these numbers should be> significantly different, suggestions on how to fix the situation are> welcome. Personally I would deprecate _cell_measurement_temperature or> state that it is only used when the cell is measured separately to the> main diffraction data set.>> James.>> --> T +61 (02) 9717 9907> F +61 (02) 9717 3145> M +61 (04) 0249 4148> _______________________________________________> coreDMG mailing list> coreDMG@iucr.org> http://mailman.iucr.org/cgi-bin/mailman/listinfo/coredmg> -- T +61 (02) 9717 9907F +61 (02) 9717 3145M +61 (04) 0249 4148_______________________________________________coreDMG mailing listcoreDMG@iucr.orghttp://mailman.iucr.org/cgi-bin/mailman/listinfo/coredmg
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- What does it mean for _diffrn_ambient_temperature and_cell_measurement_temperature to be different? (James H via coreDMG)
- Re: What does it mean for _diffrn_ambient_temperature and_cell_measurement_temperature to be different? (Spek, A.L. \(Ton\) via coreDMG)
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