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<p>Hi Branislav,</p>
<p>your input file is in principle correct. The main issue is that
the DZVP-MOLOPT-GTH basis set is really not optimized for HFX type
calculations. Therefore, a lot of time is spent calculating
4-center integrals, and even more time is spent on 4-center
derivatives.</p>
<p>I see 3 ways that you can improve your timings:</p>
<p>1) Use a basis set that is better suited. For example, Pople
style all-electron basis sets such as 6-31G* (requires a switch to
GAPW)</p>
<p>2) Use a RI approximation for the HFX: add &RI &END to
the &HF section (this requires CP2K 9.1 or more recent)</p>
<p>3) Use the ADMM method
(<a class="moz-txt-link-freetext" href="https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/AUXILIARY_DENSITY_MATRIX_METHOD.html">https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/AUXILIARY_DENSITY_MATRIX_METHOD.html</a>)</p>
<p>I think solution 1) is the easiest. I also suggest that you use
the FULL_ALL preconditioner for OT. It performs better than
FULL_S_INVERSE for smaller system (in that case, you also need to
remove the ENERGY_GAP keyword).</p>
<p>Hope that helps. Best,</p>
<p>Augustin<br>
</p>
<div class="moz-cite-prefix">On 4/26/22 16:10, Бранислав Миловановић
wrote:<br>
</div>
<blockquote type="cite" cite="mid:e568c56a-bfea-411c-9274-119d735cc83cn@googlegroups.com">
Dear CP2K users,
<div><br>
</div>
<div>I'm experiencing problems when using hybrid functionals such
as B3LYP or M062X and while optimizing simple test system
(hydrogen bonded acetic acid dimer).</div>
<div><br>
</div>
<div>SCF convergence appears to be fast and normal but the Force
calculation step is extremely slow. Maybe I made some mistake in
the input file?</div>
<div><br>
</div>
<div>I attached my input files and output file (B3LYP).</div>
<div>Also, I don't really understand the timings at the end output
file.<br>
</div>
<div><br>
</div>
<div>Thanks in advance!<br>
Branislav</div>
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<pre class="moz-signature" cols="72">--
Augustin Bussy
Postdoctoral researcher
Hutter Group
University of Zurich</pre>
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