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Hi Cyrille,<br>
<br>
At first all my calculations are not going to converge where I am
using cutoffs of (40,400), (50,500) etc. Later I tried to find the
optimal cutoffs following the recipe by Stefano:<br>
<a class="moz-txt-link-freetext" href="http://qe-forge.org/pipermail/pw_forum/2013-February/101122.html">http://qe-forge.org/pipermail/pw_forum/2013-February/101122.html</a><br>
The optimal cutoffs are actually much lower than I was using, it's
about (60,280). <br>
I did several calculations using different cutoffs for finding
optimal cutoffs, and I found the following<br>
1) Forces on atoms are basically dependent on ecutrho, while<br>
2) Total energies are basically dependent on ecutwfc<br>
3) As the cutoffs increases, the SCF convergence becomes harder and
harder.<br>
<br>
best,<br>
Yun-Peng<br>
<br>
<br>
<div class="moz-cite-prefix">On 09/12/2015 03:30 PM, BARRETEAU
Cyrille wrote:<br>
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Dear Yun-Peng,<br>
<br>
>From experience I can just say that calculation using
fully-relativistic PP can be really difficult to converge and
sometimes almost impossible to achieve the desired accuracy
(especially since magneto-crystalline anisotropy requires very
strict convergence thresholds). You can play with broadening and
k points sampling.<br>
<br>
Cyrille<br>
<br>
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<div style="direction: ltr;" id="divRpF254260"><font
face="Tahoma" color="#000000" size="2"><b>De :</b>
<a class="moz-txt-link-abbreviated" href="mailto:pw_forum-bounces@pwscf.org">pw_forum-bounces@pwscf.org</a> [<a class="moz-txt-link-abbreviated" href="mailto:pw_forum-bounces@pwscf.org">pw_forum-bounces@pwscf.org</a>] de
la part de yuewen.fang [<a class="moz-txt-link-abbreviated" href="mailto:yuewen.fang@gmail.com">yuewen.fang@gmail.com</a>]<br>
<b>Envoyé :</b> samedi 12 septembre 2015 20:42<br>
<b>À :</b> pw_forum<br>
<b>Objet :</b> Re: [Pw_forum] magnetic anisotropy
calculation using fully-relativistic PPs<br>
</font><br>
</div>
<div>
<div style="">Hi, Yun-Peng,
<div><br>
</div>
<div>Thanks for your feedback. It depends on the matter
which you are interested in. I think this paper (Phys.
Rev. B 86, 085135 (2012)) can help you.
<div><br>
</div>
<div>Bests</div>
<div>Fang<br>
<br>
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background-color:rgb(255,255,255)">
<div>
<p class="MsoNormal"><span
style="font-size:10pt" lang="EN-US"><font
face="Georgia">Yue-Wen FANG, PhD candidate</font></span></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:10pt" lang="EN-US"><font
style="word-wrap:break-word"
face="Georgia"><a moz-do-not-send="true"
href="http://english.ecnu.edu.cn/"
style="word-wrap:break-word"
target="_blank">East China Normal
University</a></font></span></p>
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<br>
<div class="gmail_quote"><span dir="ltr">< <a
moz-do-not-send="true"
href="mailto:petercybertron@gmail.com"
target="_blank">
peter</a>> 2015-09-13 02:16:28 wrote: </span><br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex; border-left:1px #ccc solid;
padding-left:1ex">
<div dir="ltr">
<div>Thank you for your suggestions!<br>
I tried using a small mixing beta (0.1~0.2),
and tried using reasonable cutoff energies
(ecutwfc=50, ecutrho=500), now the convergence
is much better than before (converged down to
10^-6 Ry).<br>
Another question is, I can find ultra-soft and
PAW pseudopotentials, which one is better for
spin-orbit calculations? I am using PBE XC
functional.<br>
<br>
best,<br>
Yun-Peng<br>
<br>
<div class="moz-cite-prefix">On 09/11/2015
08:08 PM, yuewen.fang wrote:<br>
</div>
<blockquote type="cite">
<div style="">Dear Yun-Peng,
<div><br>
</div>
<div>Plz try to decrease mixing and
perform some convergence tests for your
cutoff energy to remove the oscillation
of the energy! In addition, this
oscillation could also be caused by the
unreasonable smearing methods for
metals.</div>
<div><br>
</div>
<div>Bests</div>
<div>Fang<br>
<br>
<hr class="-eMc-email-sig"
style="width:101px; border:0;
border-top:1px solid #ccc"
align="left">
<div><a moz-do-not-send="true"
href="http://www.yomail.com/?utm_source=signature"
style="font-size:12pt"
target="_blank">Sent from YoMail</a></div>
<br>
<div class="gmail_quote"><span dir="ltr"><
<a moz-do-not-send="true"
href="mailto:petercybertron@gmail.com"
target="_blank">
Peter Cybertron</a>> 2015-09-12
03:10:31 wrote:</span><br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;
border-left:1px #ccc solid;
padding-left:1ex">
<div dir="ltr">Hi,<br>
<br>
<br>
I am working in University of
Florida as a postdoc.<br>
I am exploring the spin-orbital
calculations using pwscf, and I<br>
encounter a very slow convergence
like this:<br>
> grep estimated scf.out<br>
estimated scf accuracy <
0.00000004 Ry<br>
... (100 similar lines)<br>
estimated scf accuracy <
0.00000003 Ry<br>
> grep "total energy" scf.out<br>
...<br>
total energy = -3667.91077719 Ry<br>
total energy = -3667.91078176 Ry<br>
total energy = -3667.91077642 Ry<br>
total energy = -3667.91078300 Ry<br>
<br>
<br>
Although the convergence of total
energy seems OK (down to 0.00001
Ry ~<br>
0.0001 eV = 0.1 meV), I still feel
uncomfortable since I never
encounter<br>
such a problem without spin-orbit
interactions.<br>
<br>
<br>
I downloaded the ultrasoft and PAW
pseudopotentials from PSLib and I
am<br>
using the PBE flavor of XC
functional. The system I am
studying is a two<br>
dimensional magnetic insulator.<br>
<br>
<br>
The parameters I am using are:<br>
constrained_magnetization = 'total
direction'<br>
fixed_magnetization(3) = 0.0<br>
lambda = 0.2<br>
ecutwfc = 30.0 ,<br>
ecutrho = 300.0 ,<br>
occupations = 'smearing' ,<br>
degauss = 0.005,<br>
smearing = 'mv' ,<br>
nosym=.true.<br>
mixing_mode = 'local-TF' ,<br>
mixing_beta = 0.9 ,<br>
diagonalization = 'david' ,<br>
<br>
<br>
Which parameter on earth keep my
calculations non-converged?<br>
<br>
<br>
Best,<br>
Yun-Peng<br>
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