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<p>Hello Jakob,</p>
<p>you do not give much detail about what you are doing. As said,
QHA is effective when dealing with one degree of freedom (i.e.
cubic semiconductor) but harder to use in any other case. Are you
doing a constant-volume variable-cell relax (aka
cell_dofree='shape') for a series of volumes? And then computing
for each volume the Helmholtz free energy (from the phonons
directly or from the dos)? Are you doing this your self by hand or
using one of the available QHA software packages?</p>
<p>The oscillations could be an honest bug, or a difficult
integration of the DOS.<br>
</p>
<p>cheers<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 04/11/2022 09:20, Jakob Kraus wrote:<br>
</div>
<blockquote type="cite"
cite="mid:68c7ecda-68e4-bf8b-68af-ea7d030635f8@physik.tu-freiberg.de">Dear
QE users,
<br>
<br>
<br>
I am trying to calculate heat capacities, and to this end, I have
calculated the Gibbs energy as a function of volume
<br>
<br>
at several temperatures in a range of 0-700 K.
<br>
<br>
However, the functions that result from this do not show a single
minimum, but rather a whole lot of oscillations, which
<br>
<br>
seem to originate from the phonons, since the E(V) diagram at 0 K
shows a single minimum as expected.
<br>
<br>
I am thankful for any help you can offer with getting rid of these
oscillations.
<br>
<br>
I have attached input files and some plots to showcase the
problem.
<br>
<br>
<br>
Best regards,
<br>
<br>
<br>
Jakob Kraus, TU Freiberg
<br>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
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<div class="moz-signature">-- <br>
<small>Dr. Lorenzo Paulatto<br>
IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université<br>
phone: +33 (0)1 442 79822 / skype: paulatz<br>
<a href="http://www.impmc.upmc.fr/~paulatto/"
class="moz-txt-link-freetext">http://www.impmc.upmc.fr/~paulatto/</a>
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