<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Right now I am testing some desperate approaches like increasing k-points, decreasing mixing_beta together with trust_radii to force systems to change sightly fro step to step in vc-relax, etc.</div><div class=""><br class=""></div><div class="">I also thought that more precise calculation of stresses (in vc-relx routine) might help, does anyone have experience with parameters involved in stress calculations like <span style="font-size: 14px;" class="">ecfixed, qcutz, q2sigma</span>?</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">
<div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">Best,<br class="">Alex.<br class="">___<br class="">Aleksandra Oranskaia (M.Sc.)<br class="">ChemS PhD student, KAUST<br class="">Phone: +966 50 1335254<br class=""><br class=""><br class=""></div><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""></div><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline">
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<br class=""><div><blockquote type="cite" class=""><div class="">On Apr 6, 2019, at 1:00 PM, <a href="mailto:users-request@lists.quantum-espresso.org" class="">users-request@lists.quantum-espresso.org</a> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Send users mailing list submissions to<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span><a href="mailto:users@lists.quantum-espresso.org" class="">users@lists.quantum-espresso.org</a><br class=""><br class="">To subscribe or unsubscribe via the World Wide Web, visit<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>https://lists.quantum-espresso.org/mailman/listinfo/users<br class="">or, via email, send a message with subject or body 'help' to<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>users-request@lists.quantum-espresso.org<br class=""><br class="">You can reach the person managing the list at<br class=""><span class="Apple-tab-span" style="white-space:pre"> </span>users-owner@lists.quantum-espresso.org<br class=""><br class="">When replying, please edit your Subject line so it is more specific<br class="">than "Re: Contents of users digest..."<br class=""><br class=""><br class="">Today's Topics:<br class=""><br class=""> 1. vc-relax for orthorhombic systems (Aleksandra Oranskaia)<br class=""><br class=""><br class="">----------------------------------------------------------------------<br class=""><br class="">Message: 1<br class="">Date: Fri, 5 Apr 2019 19:39:39 +0300<br class="">From: Aleksandra Oranskaia <aleksandra.oranskaia@kaust.edu.sa><br class="">To: Quantum Espresso users Forum <users@lists.quantum-espresso.org><br class="">Subject: [QE-users] vc-relax for orthorhombic systems<br class="">Message-ID: <8FCA3967-9817-4748-B8D3-34EC6F0295A2@kaust.edu.sa><br class="">Content-Type: text/plain; charset="iso-8859-1"<br class=""><br class="">Dear QE users and developers,<br class=""><br class="">1 When dealing with orthorhombic systems, I start with space_group super-tight relaxation of the atomic positions (keeping right balance in force and scf accuracy, increasing ecutrho plus 100 Ry than my system actually requires, etc), continue with vc-relax using dofree = ibrav (and press_thr = 0.0), and Always obtain at least one lattice constant screwed up (with an error like +/- 0.1 A as compared to the experimental constant).<br class="">I tried 1000 setups for a few systems (varying functionals, vdw corrections, different pseudo libraries, etc) and have a feeling that sth is not right with vc-relax: for other than orthorhombic systems the results match the experimental lattice constants with an acceptable error.<br class=""><br class="">2 I was wondering how vc-relax work for big orthorhombic unit cells. I took alpha-S8 (space group 70, so 128 atoms turn into 32 within ibrav = 10 with 8 symmetry elements) and am not satisfied with any lattice constants: on PBEsol level, error in volume is <1% as compared to the experimental unit cell, but lattice constants are like 10.602 (exp: 10.465), 12.937 (exp: 12.866), 24.286 (exp: 24.486) A that do not look acceptable at all :-(<br class=""><br class="">I would hugely appreciate any comments,<br class=""><br class=""><br class="">Thanks,<br class="">Alex.<br class="">___<br class="">Aleksandra Oranskaia (M.Sc.)<br class="">ChemS PhD student, KAUST<br class="">Phone: +966 50 1335254<br class=""><br class=""><br class=""><br class=""><br class=""><br class=""><br class=""><br class="">-- <br class=""><br class="">This message and its contents, including attachments are intended solely <br class="">for the original recipient. If you are not the intended recipient or have <br class="">received this message in error, please notify me immediately and delete <br class="">this message from your computer system. Any unauthorized use or <br class="">distribution is prohibited. Please consider the environment before printing <br class="">this email.<br class="">-------------- next part --------------<br class="">An HTML attachment was scrubbed...<br class="">URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20190405/7ab54d9a/attachment-0001.html><br class=""><br class="">------------------------------<br class=""><br class="">Subject: Digest Footer<br class=""><br class="">_______________________________________________<br class="">users mailing list<br class="">users@lists.quantum-espresso.org<br class="">https://lists.quantum-espresso.org/mailman/listinfo/users<br class=""><br class="">------------------------------<br class=""><br class="">End of users Digest, Vol 141, Issue 6<br class="">*************************************<br class=""></div></div></blockquote></div><br class=""></body></html>
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