Dear Purity Following on from Gerard's response, your question is in two parts:
1. How can you improve my R values where there is anisotropy ? If you haven't done so already I would suggest that you try submitting the data to the STARANISO server https://staraniso.globalphasing.org/cgi-bin/staraniso.cgi (carefully following the recommendations and instructions on the website). Then repeat the refinement and map calculation - though there are no guarantees that it will improve your R values (but it may well improve the interpretability of your maps). 2. What is the cause of diffraction anisotropy ? I think the answer to this question is well established: the crystal diffraction limit is dependent on the number and strength of intermolecular contacts (typically H-bonds and salt bridges, but could also be covalent bonding such as S-S bridges and cross-links). Fewer and/or weaker contacts allows a greater degree of thermal motion and/or static disorder either generally (isotropic case) or in specific directions (anisotropic case) which manifests in correspondingly faster fall-off of the intensities in all or just those specific directions. Hope this helps! -- Ian (Global Phasing) On Wed, 21 Jan 2026 at 17:58, Ezennubia, Purity < [email protected]> wrote: > Hello everyone, > > It's becoming almost a regular norm for my crystals to be anisotropic when > I look at the diffraction data. Its really unideal for me because when the > data is anisotropic my R-work and R-free values are usually high when > compared to some lucky data I got that was not anisotropic. > > I would like to hear from other people in this forum what causes a crystal > to diffract anisotropically going to different resolution in the hkl axis. > > Thank you, > Purity > > *Kelechi Purity Ezennubia* > *Graduate research assistant * > *Department of Chemistry & Biochemistry * > *Baylor University * > *Clinger lab C161R* > *[email protected] <[email protected]>* > > ------------------------------ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
