<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Dear Sir/Madam,<div class=""><br class=""></div><div class="">I recently came across a question about the crystal structure of the element gadolinium. One of our users had shown me a double-hexagonal-close-packed (“dhcp") structure, but <i class="">Wyckoff</i> claimed the element had a simple hcp structure. We took a look at your database and found that one of your structures appears to be incorrect. Here are the details:-</div><div class=""><br class=""></div><div class="">COD ID: <b class="">1526591</b></div><div class=""><br class=""></div><div class="">There are two issues here:-</div><div class=""><br class=""></div><div class="">1. Spelling mistake in the journal title “Supercondunctivity” (remove the second ’n’).</div><div class=""><br class=""></div><div class="">2. The structure makes no sense.</div><div class=""><br class=""></div><div class="">- I don’t know whether some information has been lost here, but your CIF file lists only a single site, at {1/2, 1/2, 1/2} - which is a (very) special position. When plotted, this quite large unit cell only has this single atom - which is clearly incorrect.</div><div class=""><br class=""></div><div class="">- If one is using an orthorhombic unit cell (for what is effectively an hexagonal lattice), then I would expect the ‘a’ or ‘b’ parameter to be much larger, something on the order of 6.3 Å (=2 . aH . cos(30), where ‘aH’ is the hexagonal parameter) - unless this is supposed to be some kind of derivative of the higher-temperature (“beta”) bcc lattice.</div><div class=""><br class=""></div><div class="">I hope this information helps!</div><div class=""><br class=""></div><div class="">With best wishes,</div><div class=""><br class=""></div><div class="">David Palmer</div><div class="">Managing Director,</div><div class="">CrystalMaker Software Ltd</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><i class="">CrystalMaker is a user-funded project to provide the very-best software for crystal and molecular structures modelling.</i></div><div class=""><i class=""><br class=""></i></div><div class=""><i class="">We receive no EU subsidies, government bailouts, university salaries, pensions or student fee income. Everything we do is funded by our users - not the general taxpayer. It’s the only honest and sustainable way of providing quality software for the long term.</i></div></body></html>