<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Dear Colleagues,<div><br></div><div>I send you a message a few weeks ago about my plans to provide easy phase ID via C.O.D.-hosted structures. I haven’t heard back from you, so I assume you have no objections.</div><div><br></div><div>In the meantime, we have used our automated tools to analyse all current structures files. I am attaching a summary, listing file IDs and errors for 2,997 out of your 0.5M or so files: a relatively-small figure (ca. 0.6%). However, these files are invalid, and cannot be used for structural work, so I would recommend getting them fixed.</div><div><br></div><div>The most common errors are:</div><div><br></div><div>- missing fractional coordinates</div><div>- ambiguous site labelling</div><div>- invalid element symbols</div><div><br></div><div>A common issue is a mismatch between site labels in different data blocks (e.g., a table of anisotropic displacement parameters and a table of fractional coordinates). We found these errors in numerous files submitted via the <b>American Mineralogist crystal structures database</b> (clearly, substantial amounts of U.S. governmental funding failed to prevent basic transcription errors!)</div><div><br></div><div>Take the following file, 9003355, as an example:-</div><div><br></div><div>• Sites SiT1’, AlT1’ (etc.) are listed in the loop containing Uij</div><div>• The same site are labelling differently (e.g., SiT1*, AlT1*, etc.) in the loop containing xyz</div><div><br></div><div>Whilst, to a human, one could make inferences as to how these labels should be related, a computer cannot make such a judgement, thereby rendering these files useless.</div><div><br></div><div>I hope this helps, and do let me know if you have any questions.</div><div><br></div><div>With best wishes,</div><div>Yours faithfully,</div><div><br></div><div>David Palmer</div><div><br></div><div><div style="font-family: MinionPro-Regular;">David C Palmer, Ph.D. (Cantab), M.A. (Cantab),</div><div style="font-family: MinionPro-Regular;">Managing Director, CrystalMaker Software Ltd</div><div style="font-family: MinionPro-Regular;">Centre for Innovation & Enterprise | Oxford University Begbroke Science Park</div><div style="font-family: MinionPro-Regular;">Woodstock Road, Begbroke, Oxfordshire, OX5 1PF, UK</div></div><div style="font-family: MinionPro-Regular;"><br></div><div><font face="MinionPro-Regular"></font></div><br />--
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