For all who asked about observed differences in bond rmsd reported by phenix.refine and Refmac, H atoms included in statistics calculation and more... 1) First, I wanted to check bond rmsd reported by phenix.refine. I made up a PDB file containing just one residue (SER, no H atoms) and I wrote a crystal-clear and simple Python script that computes bond rmsd for this residue. Here are the numbers: Bond length rmsd: Script: 0.148 phenix.pdbtools: 0.148 phenix.refine: 0.148 Refmac_5.5.0070: 0.152 Both programs are using the Monomer Library. Since both of these very different ways of computing bond rmsd: this simple script and phenix.refine, give the identical values, I tend to think that the PHENIX implementation is actually correct. I have no idea why Refmac gives a different value and I think it's now up to Refmac developers (or any other enthusiast) to find it out or show that I'm wrong in my calculations. It well could also be me who's incorrectly using Refmac - today was my second time I tried it (the first was 3 or 4 years ago) -:) As for the bond angles rmsd, I didn't bother to include it into the script, but for the rest of tools in question, the numbers are: phenix.pdbtools: 16.628 phenix.refine: 16.628 Refmac_5.5.0070: 16.628 so all results seem to be in-sync. 2) Some people reported that the geometry statistics for the exact same structure with and without hydrogens seems to be reported different in phenix.refine. To find out, I did the same test as above, where I used the same one residue model with all hydrogens added. Unfortunately, I failed to make Refmac accept a PDB file containing H atoms so I gave up after 20 minutes of struggle. Here are the numbers: Bond length rmsd: Script: 0.155 phenix.pdbtools: 0.155 phenix.refine: 0.155 So, it seems like the hydrogens are included... I have to fix it. Well at least those who are doing refinement using neutron data or both X-ray and neutron data, were not concerned, since in that case I presume the H and D atoms should be included. Anyway, I'm fixing it right now, I'm making a corresponding regression test (to make sure the fix stays there forever) and the fixed version will be available in the next release. By the way, the new tool, phenix.model_vs_data is and was smart about this: it automatically excludes H and D atoms if X-ray data is used. And this proves it: phenix.model_vs_data: 0.148 which is the exact same number as in "1)", where H were not present. Thanks to all who raised this issue (Frank von Delft, Jianghai Zhu, Karolina Michalska and others)! Pavel. PS> All files used and the script are here: http://cci.lbl.gov/~afonine/rmsd_issue/ Use "phenix.python run.py" to run the script.