Hi It's pretty much what the powder people do when using Rietveld refinement, isn't it? As far as I know, they fit a calculated curve from their structure to a 1D trace of the powder pattern (happy to be corrected on this). All you need to do is extend this to 3D - there may be enough work there for a project student ;-).
Harry -- Dr Harry Powell > On 30 Jul 2019, at 10:47, Loes Kroon-Batenburg <l.m.j.kroon-batenb...@uu.nl> > wrote: > > Dear Jacob, > > That should indeed be our ultimate goal: refining against the image data > rather than against process data. This would require a good model for the > crystal, mosaicity being an important parameter in this, and for the internal > variation in the molecular structure. Modelling the Bragg spots is what we do > currently wth EVAL. James Holton is doing also this with nanoBragg. > Unfortunately we would also have to simulate solvent rings etc. > > Best wishes, > Loes >> On 07/25/19 19:07, Keller, Jacob wrote: >> >>It would seem to me that an important issue is also: do get all >> >>information out of our diffraction data? By integrating the Bragg peaks we >> >>usually neglect the diffuse scattering that could potentially contain >> >>additional (dynamic) structural information. This can be cloudy diffuse >> >>scattering hidden in the background but also diffuse streaks that contain >> >>information on packing disorder and reveals intrinsic interactions in the >> >>crystal. >> >> Along these lines, and taking a page from you also, how about >> “crystallographic model refinement as image-faking?” Metrics of the goodness >> of a particular refinement could simply be some measure of the correlation >> between predicted vs. measured images. I have seen some of this done with >> diffuse scattering, but why not with the whole thing, including intensity >> and shape of Bragg peaks, solvent rings, etc? Maybe instead of doing the >> multiple steps of (indexing, integration, scaling, solving…) all of this >> could be refined as one? Processing parameters like moscaicity [sic] etc >> would now be part of the final model…? >> >> JPK >> >> >> >> >> Loes Kroon-Batenburg >> >> On 07/15/19 21:44, Holton, James M wrote: >> Hello folks, >> >> I have the distinct honor of chairing the next Gordon Research >> Conference on Diffraction Methods in Structural Biology (July 26-31 >> 2020). This meeting will focus on the biggest challenges currently >> faced by structural biologists, and I mean actual real-world >> challenges. As much as possible, these challenges will take the form of >> friendly competitions with defined parameters, data, a scoring system, >> and "winners", to be established along with other unpublished results >> only at the meeting, as is tradition at GRCs. >> >> But what are the principle challenges in biological structure >> determination today? I of course have my own ideas, but I feel like I'm >> forgetting something. Obvious choices are: >> 1) getting crystals to diffract better >> 2) building models into low-resolution maps (after failing at #1) >> 3) telling if a ligand is really there or not >> 4) the phase problem (dealing with weak signal, twinning and >> pseudotranslation) >> 5) what does "resolution" really mean? >> 6) why are macromolecular R factors so much higher than small-molecule ones? >> 7) what is the best way to process serial crystallography data? >> 8) how should one deal with non-isomorphism in multi-crystal methods? >> 9) what is the "structure" of something that won't sit still? >> >> What am I missing? Is industry facing different problems than >> academics? Are there specific challenges facing electron-based >> techniques? If so, could the combined strength of all the world's >> methods developers solve them? I'm interested in hearing the voice of >> this community. On or off-list is fine. >> >> -James Holton >> MAD Scientist >> >> >> ######################################################################## >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 >> >> >> >> -- >> >> __________________________________________ >> >> Dr. Loes Kroon-Batenburg >> Dept. of Crystal and Structural Chemistry >> Bijvoet Center for Biomolecular Research >> Utrecht University >> Padualaan 8, 3584 CH Utrecht >> The Netherlands >> >> E-mail : l.m.j.kroon-batenb...@uu.nl >> phone : +31-30-2532865 >> fax : +31-30-2533940 >> __________________________________________ >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 >> > > > -- > > __________________________________________ > > Dr. Loes Kroon-Batenburg > Dept. of Crystal and Structural Chemistry > Bijvoet Center for Biomolecular Research > Utrecht University > Padualaan 8, 3584 CH Utrecht > The Netherlands > > E-mail : l.m.j.kroon-batenb...@uu.nl > phone : +31-30-2532865 > fax : +31-30-2533940 > __________________________________________ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
