<div dir="ltr"><div dir="auto">Thank you all for your suggestions. I think the best move would be to increase the smearing value until I achieve convergence. I also wanted to ask, but would mixing = 'local-tf' be a good mixing method for this system? The crystal has been confirmed experimentally to be a metal, and I the elongated unit cell prompted my initial use of it, however I've never changed the mixing method before so I'm not exactly sure if this is the right step to take.</div><div dir="auto"><br></div><div>Best,</div><div>Stephen<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jan 25, 2021, 8:04 AM Stefano Baroni <<a href="mailto:baroni@sissa.it" target="_blank">baroni@sissa.it</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>We do not necessarily disagree. The internal energy is harder to converge than the free energy, because the first is not variational, whereas the latter is so. Also, level crossing is obviously much reduced (and eventually eliminated) for large enough smearing. S.<br><div><br><blockquote type="cite"><div>On 25 Jan 2021, at 16:59, Nicola Marzari <<a href="mailto:nicola.marzari@gmail.com" rel="noreferrer" target="_blank">nicola.marzari@gmail.com</a>> wrote:</div><br><div>
<div>
<div><br>
</div>
<div><br>
</div>
<div>Dear Stefano, Lucas,</div><p>this is one of the few areas where I disagree with Stefano - I
think we should use the free energy (forces and stresses are the
total derivative of the free energy, not the internal energy), and
that level-crossing instabilities are exceedinfly difficult to
cure with iterative algorithms (my own opinions are here:
<a href="http://theossrv1.epfl.ch/Main/ElectronicTemperature" rel="noreferrer" target="_blank">http://theossrv1.epfl.ch/Main/ElectronicTemperature</a>),</p>
<div><br>
</div>
<div> nicola</div>
<div><br>
</div>
<div><br>
</div>
<div>On 25/01/2021 16:33, Stefano Baroni
wrote:<br>
</div>
<blockquote type="cite">
I beg to slight differ. It does not make much sense to assign a
“default value” to the Gaussian smearing, unless one makes sure
that the computations are well converged with respect to the
number of k points, for that specific value of the smearing. The
rational procedure to follow is: 1) start with whatever value of
the smearing one wishes, and make sure that the (internal, *not*
“fake free”) energy is well converged with respect to the number
of k points. If the number of k points is sufficient, it is likely
that no nasty oscillation would arise; 2) decrease the smearing
and vary the number of k points accordingly. HTH — Stefano B
<div><br>
</div>
<div><br>
<div>
<div dir="auto" style="letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none">
<div dir="auto" style="letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none">
<div dir="auto" style="letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration:none">
<div style="font-size:12px">—<br>
Stefano Baroni - SISSA, Trieste - <a href="http://stefano.baroni.me/" rel="noreferrer" target="_blank">http://stefano.baroni.me</a>,
stefanobaroni (skype)<br>
<br>
I do not mind if you think slowly, but I do object
when you publish more quickly than you think [W.E.
Pauli to an unknown colleague, as reported by N.
Kemmer]</div>
</div>
</div>
</div>
</div>
<div><br>
<blockquote type="cite">
<div>On 25 Jan 2021, at 15:08, Lucas Nicolás
Lodeiro Moraga <<a href="mailto:lucas.lodeiro@ug.uchile.cl" rel="noreferrer" target="_blank">lucas.lodeiro@ug.uchile.cl</a>>
wrote:</div>
<br>
<div>
<div dir="ltr">Hi,
<div>It appears a metallic oscillation, where a
couple or more states change their relative energy,
and change their energetical order, then the
occupation changes abruptly (non continuous). If this
is the problem, it is better to increase the degauss
value and/or change the smearing method.</div>
<div>Typically I use methfessel-paxton with
0.015 Ry for degauss, which mimics the VASP default
values. When you get a converged system, you can try
to decrease (slowly) the degauss.</div>
<div><br>
</div>
<div>Regards - Lucas Lodeiro</div>
</div>
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_______________________________________________<br>Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu" rel="noreferrer" target="_blank">www.max-centre.eu</a>)<br>users mailing list <a href="mailto:users@lists.quantum-espresso.org" rel="noreferrer" target="_blank">users@lists.quantum-espresso.org</a><br><a href="https://lists.quantum-espresso.org/mailman/listinfo/users" rel="noreferrer" target="_blank">https://lists.quantum-espresso.org/mailman/listinfo/users</a></div></blockquote></div><br></div>_______________________________________________<br>
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