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<p>Dear Thomas,</p>
<p><br>
</p>
<p><font size="4" face="OpenSans" color="black" style="font-family:OpenSans,serif,"EmojiFont""><span id="x_divtagdefaultwrapper" style="font-size:14pt">> ...the difference might come from some details in the implementation of +U or from some things related
to the pseudo</span></font><br>
</p>
<p><br>
</p>
<p>Indeed, the difference in pseudos might have an impact. But also there are important differences in the DFT+U implementations:</p>
<p>- in VASP the PAW Hubbard projectors are used</p>
<p>- in QE the atomic or ortho-atomic Hubbard projectors are typically used (but you can also try the PAW projectors but this requires pseudos with AE wavefunctions, see
<span>PWCOND/examples</span>/<span>example03</span>)</p>
<p><br>
</p>
<p>HTH</p>
<p><br>
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<p><span style="font-family:Constantia,"Hoefler Text",serif">Iurii</span><br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Kazume NISHIDATE <nisidate@iwate-u.ac.jp><br>
<b>Sent:</b> Monday, November 28, 2022 12:21:47 AM<br>
<b>To:</b> Quantum ESPRESSO users Forum<br>
<b>Cc:</b> Vivekanand Shukla; Iurii TIMROV<br>
<b>Subject:</b> Re: [QE-users] Problem in vc-relax calculation with Hubbard U in magnetic system</font>
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<div class="PlainText">Dear Thomas Brumme,<br>
<br>
I'm not familiar with the +U method and this is a general view.<br>
<br>
- One possibility is the difference in the relaxation route achieving<br>
the most stable state. In some cases, the system may be trapped in<br>
quasi stable state.<br>
<br>
Suppose that you get structure A in QE and structure B in VASP, both<br>
starting from the original structure G, you can compare the relative<br>
energies by performing the static scf calculations for A, B, and G.<br>
<br>
If both of the codes return the same order of energies, such as E(A)<br>
< E(B) < E(G), you can safely identify the stable structure (in this<br>
case the structure A). Be careful about the k-points and cutoff <br>
energies. The number of PWs of A must be different from that<br>
of B and you must maintain the accuracy by increasing the k-points<br>
and the cutoff.<br>
<br>
- Are you using dense k-points mesh and high cutoff energies in the<br>
relaxation process too?<br>
<br>
- Of course the difference of the pseudo/PAW potentials may influence<br>
the results. This is the reason why the VASP has variety of<br>
pseudo/PAW potentials for some elements. Try the same calculations<br>
using different pseudo/PAW sets.<br>
<br>
- Try the VASP relaxations without +U option. Will it return the same<br>
structure with +U?<br>
<br>
<br>
<br>
> 2022/11/28 0:43$B!"(BThomas Brumme <thomas.brumme@tu-dresden.de>$B$N%a!<%k(B:<br>
<br>
> In VASP the relaxation is not restricted and since both codes use more or less the same theory, the difference might come from some<br>
> details in the implementation of +U or from some things related to the pseudo. Do you have any feeling/idea if changing to a different<br>
> pseudo or something different concerning +U might influence the relaxation?<br>
> <br>
> Kind regards<br>
> <br>
> Thomas<br>
<br>
<br>
$B@>4[?t2j(B<br>
Kazume NISHIDATE Ph.D<br>
<br>
Department of Systems Innovation Engineering,<br>
Graduate School of Science and Engineering, Iwate University<br>
4-3-5 Ueda, Morioka, Iwate, 020-8551 JAPAN<br>
Phone:+81-19-621-6391<br>
kazume.nishidate@gmail.com, nisidate@iwate-u.ac.jp<br>
<a href="https://sites.google.com/site/nisidatelab/">https://sites.google.com/site/nisidatelab/</a><br>
<br>
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