[ccp4bb] RA position in Crysalin technology

Hello, We have the below position available in the Frank von Delft lab at the SGC Oxford, applications are to be made online but I am happy yo respond ta any questions you may have. Cheers Mike https://www.jobs.ac.uk/job/CAR123/research-assistant-in-crysalin-technology Nuffield Department of M

Re: [ccp4bb] Quote source inquiry

Close enough verbatim and dead on in spirit. Many thanks, BR -Original Message- From: Gerard DVD Kleywegt Sent: Wednesday, July 15, 2020 08:49 To: b...@hofkristallamt.org Cc: CCP4 Bulletin Board Subject: Re: [ccp4bb] Quote source inquiry Well, I've had this in my CSHL X-ray Course talk

Re: [ccp4bb] Quote source inquiry

Hi Gerard and Bernhard, As a postdoc in an unnamed small molecule lab, I was instructed by my lab head to get better unit cell estimates prior to data collection owing to error propagation from the uncertainty on cell dimensions through to the esd on atomic bond lengths and angles when refining

Re: [ccp4bb] Quote source inquiry

Thanks - very interesting paper, Jeffrey. I think your analysis is correct, but you forgot: (4) the skill of the crystallographer... Best wishes, --Gerard On Wed, 15 Jul 2020, Jeffrey B Bonanno wrote: Hi Gerard and Bernhard, As a postdoc in an unnamed small molecule lab, I was instructed

Re: [ccp4bb] Quote source inquiry

:: took a working dataset and increased (only) the error on unit cell dimensions in the instruction file for the final round of full matrix :: least squares refinement in shelxl. Sure enough, the errors on the bonds and angles shot up. I was more careful Question: did you change the unit cell d

Re: [ccp4bb] Quote source inquiry

Hi Phil, Being young and impressionable, I only changed ZERR, and you are quiet right the result is the rigorous and expected error propagation of shelxl. Of course the more fun experiment would be in systematically changing various values in UNIT to watch the molecule distort. Hope all is wel

Re: [ccp4bb] Quote source inquiry

Hi, There's one big difference between macromolecular and small molecule refinement: except at ultra-high resolution the bond lengths in the former are almost always strongly restrained, whereas those in the latter are almost without exception completely unrestrained (except possibly bond lengths

Re: [ccp4bb] Quote source inquiry

Hello, being a pedant, I guess you mean 'cell': http://xray.chem.ualberta.ca/xray/shelxl/cell.htm rather than 'unit': http://xray.chem.ualberta.ca/xray/shelxl/UNIT.htm ;-? Best wishes, Jon Cooper Original Message On 15 Jul 2020, 17:55, Jeffrey B Bonanno wrote: > Hi Phil, >

Re: [ccp4bb] Quote source inquiry

Hi Ian, Errors in cell dimensions can have a large effect in MX with certain refinement doctrines. The school of "bond length rmsd must be $NUMBER" (which is still going strong unfortunately) will suffer from poor R-factors because the target cannot be satisfied without harming the fit to the d

Re: [ccp4bb] Quote source inquiry

Hi Robbie Yes I was (perhaps rashly!) assuming that the data are properly weighted relative to the restraints. Thanks for pointing that out. Cheers -- Ian On Wed, 15 Jul 2020 at 20:23, Robbie Joosten wrote: > Hi Ian, > > Errors in cell dimensions can have a large effect in MX with certain >