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<div class="moz-cite-prefix">Dear Robert Wexler,</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">there are some additional force terms
when using Vanderbilt Ultrasoft pseudopotentials in HFX
calculations. These are not implemented, and using a more recent
QE version will actually stop, because these force terms are
missing.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Regards,</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">Tobias Klöffel <br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">On 5/13/19 5:33 PM, Robert Wexler
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAJCe4LudFJD57-Q6W0S3nX3t43CZB7EA-hp9M0zNAm1awEgJmw@mail.gmail.com">
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<div>Dear QE users,</div>
<div><br>
</div>
<div>I obtained some perplexing results using the HSE XC
functional that I would like to share with you.</div>
<div><br>
</div>
<div>I calculated the ground state potential energy surfaces
of H2 and O2 as a function of bond length strain (i.e. %
different from some arbitrary starting bond length). The
results are attached in this email as
"h2-compare-force-energy.pdf" and
"o2-compare-force-energy.pdf", respectively. The right panel
for H2 and O2 shows the total energy as a function of bond
length strain. As you can see, a slight contraction of the
original bond length is preferred. If you look at the left
panel, however, the total force is minimized at positive
strains of greater magnitude. The minimum force and total
energy should occur at the same bond length strain, which
could present some problems for geometry optimization. I
have attached inputs and outputs for each calculation in
.tar.gz files ("h2-qe-in-out.tar.gz" and
"o2-qe-in-out.tar.gz").</div>
<div><br>
</div>
<div>I took this one step further and tried to relax a water
molecule using HSE and found that the relaxation does not
converge. This can be seen in "h2o-hse-relax.pdf". As the
BFGS proceeds, it cannot converge because one configuration
decreases the total energy (steps 1, 4-12, 15-16) and
another decreases the total force (steps 2-3, 13-14).</div>
<div><br>
</div>
<div>Here is a quick summary of my computational resource and
QE settings:</div>
<div>- Cori, NERSC, KNL</div>
<div>- QE 6.3</div>
<div>- GBRV PSPs</div>
<div>- SCF calculation</div>
<div>- 35/350 Ry cutoffs</div>
<div>- LSDA for O2 (I get the correct total/absolute spin
magnetization of the O2 molecule)</div>
<div>- HSE, 1x1x1 q-grid</div>
<div>- Assume isolated, "mt"</div>
<div>- Gamma point</div>
<div>- More details can be found in the inputs and outputs
I've supplied</div>
<div><br>
</div>
<div>Thank you in advance for any help you can provide.</div>
<div><br>
</div>
<div>Best,</div>
<div>Rob</div>
<div>
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<div><span style="font-size:12.8px">---------------------------------------------</span><br>
</div>
<div>Robert B. Wexler, PhD</div>
<div>University of Pennsylvania, 2019</div>
<div><a href="mailto:rwexler@sas.upenn.edu"
target="_blank" moz-do-not-send="true">rwexler@sas.upenn.edu</a></div>
<div>(215) 801-8741</div>
<div>---------------------------------------------<br>
<br>
</div>
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</blockquote>
<p><br>
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<pre class="moz-signature" cols="72">--
M.Sc. Tobias Klöffel
=======================================================
Interdisciplinary Center for Molecular Materials (ICMM)
and Computer-Chemistry-Center (CCC)
Department Chemie und Pharmazie
Friedrich-Alexander-Universität Erlangen-Nürnberg
Nägelsbachstr. 25
D-91052 Erlangen, Germany
Room: 2.305
Phone: +49 (0) 9131 / 85 - 20423
Fax: +49 (0) 9131 / 85 - 26565
=======================================================
E-mail: <a class="moz-txt-link-abbreviated" href="mailto:tobias.kloeffel@fau.de">tobias.kloeffel@fau.de</a>
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