My answer is not precise, I just try to give students something they can remember, so they don't go and model water for example at an inappropriate resolution. Of course phasing matters as well.
On Thu, Jan 11, 2018 at 2:31 PM, Keller, Jacob <kell...@janelia.hhmi.org> wrote: >>I tell people it is when your resolution is less than the bond length that >>connects the two atoms. > > I thought this was sort of a pitfall, since the Bragg spacings don't > necessarily map on to conventional resolution. But it would fit the 1.5 Ang > estimate. > > Also, resolution would depend a lot on phase accuracy/precision, no? > > JPK > > > On Thu, Jan 11, 2018 at 1:59 PM, Thomas Edwards <t.a.edwa...@leeds.ac.uk> > wrote: >> Dear Jacob, >> >> Ah... this old chestnut! >> >> Current EM people say that they are at atomic resolution because they >> are building atomic models (naive??). >> >> I have been criticised in the past for using the term with say 2.2A >> diffraction data. By co-authors and reviewers alike. When I was young >> and naive. >> >> My (current) definition would be yours - visible with data. >> I think 1.5A is about right for X-ray. Maybe higher res? >> >> I’m sure there are lots of rigorous ways to think. I probably haven’t >> taken that route. However, I think it is a semantic problem that might >> benefit from some disambiguation rather than rigour. >> >> It depends why you are asking the question... >> >> Sorry..! >> >> Ed is: Out and about... >> Sent from iPhone6sPlus. >> >> On 11 Jan 2018, at 19:31, Keller, Jacob <kell...@janelia.hhmi.org> wrote: >> >> Dear Crystallographers, >> >> >> >> Has there been a consensus as to what is meant by “atomic resolution?” >> Seems like the term is taken by various practitioners to mean different >> things. >> >> >> >> A related question: at what resolution are atoms “visible” using only >> the data? I have an empirical feeling that this would be around 1.5 >> Ang Bragg spacings, but on the other hand, one can contour up most >> maps and see individual atom peaks. I would be interested to hear a >> more rigorous way to think about this. >> >> >> >> All the best, >> >> >> >> Jacob Keller >> >> >> >> +++++++++++++++++++++++++++++++++++++++++++++++++ >> >> Jacob Pearson Keller >> >> Research Scientist / Looger Lab >> >> HHMI Janelia Research Campus >> >> 19700 Helix Dr, Ashburn, VA 20147 >> >> (571)209-4000 x3159 >> >> +++++++++++++++++++++++++++++++++++++++++++++++++ >> >> >> >> The content of this email is confidential and intended for the >> recipient specified in message only. It is strictly forbidden to share >> any part of this message with any third party, without a written consent of >> the sender. >> If you received this message by mistake, please reply to this message >> and follow with its deletion, so that we can ensure such a mistake >> does not occur in the future. >> >>
