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<p>Dear Sergey,</p>
<p><br>
</p>
<p><span>> I have more general question - it seems that whole idea to use U correction if the system under study is metallic in plain DFT, and using DFT+U brings the system to the correct ground state. The system I study is a MOF with Mn atoms. It is already
insulating (band gap ~1.8 eV from DFT), but I guess U correction will increase band gap even more. I wonder if I really need to use U correction. Unfortunately, the material is not well studied, and experimental paper does not provide much information about
electronic structure - just geometry (cif) and ferroelectric properties are reported.</span><br>
</p>
<p><br>
</p>
<p>I am not familiar with DFT+U studies of MOFs, so I cannot comment much. Concerning DFT+U for band gaps, please see here:
<a href="http://theossrv1.epfl.ch/Main/DFTHubbard" class="OWAAutoLink" id="LPlnk268289" previewremoved="true">
http://theossrv1.epfl.ch/Main/DFTHubbard</a></p>
<p><br>
</p>
<p>Greetings,</p>
<p>Iurii<br>
</p>
<p><br>
</p>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">--<br>
Dr. Iurii TIMROV<br>
Postdoctoral Researcher<br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080"><font size="3" face="'Times New Roman', Times, serif" color="808080">Swiss Federal Institute of Technology Lausanne (EPFL<font color="808080"><font face="'Times New Roman', Times, serif">)</font></font></font><br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">CH-1015 Lausanne, Switzerland<br>
+41 21 69 34 881</font></div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> users <users-bounces@lists.quantum-espresso.org> on behalf of Sergey Lisenkov <proffess@yandex.ru><br>
<b>Sent:</b> Wednesday, August 26, 2020 12:51:07 PM<br>
<b>To:</b> Quantum ESPRESSO users Forum<br>
<b>Subject:</b> Re: [QE-users] U calculation, different projection type</font>
<div> </div>
</div>
<div>
<div>Dear Iurii, Lorenzo</div>
<div> </div>
<div>Thanks for prompt reply.</div>
<div> </div>
<div>I'll compare properties of the system I'm investigating, using both projection types.</div>
<div> </div>
<div>I have more general question - it seems that whole idea to use U correction if the system under study is metallic in plain DFT, and using DFT+U brings the system to the correct ground state. The system I study is a MOF with Mn atoms. It is already insulating
(band gap ~1.8 eV from DFT), but I guess U correction will increase band gap even more. I wonder if I really need to use U correction. Unfortunately, the material is not well studied, and experimental paper does not provide much information about electronic
structure - just geometry (cif) and ferroelectric properties are reported.</div>
<div> </div>
<div>Thanks,</div>
<div> Sergey Lisenkov</div>
<div> </div>
<div> </div>
<div> </div>
<div>26.08.2020, 12:14, "Timrov Iurii" <iurii.timrov@epfl.ch>:</div>
<blockquote>
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<p style="margin-bottom:0;margin-top:0">Dear Sergey,</p>
<p style="margin-bottom:0;margin-top:0"> </p>
<p style="margin-bottom:0;margin-top:0">As Lorenzo said, yes this is expected. Ab initio U depends on the Hubbard manifold, i.e. which projector functions are used (e.g. atomic, orthogonalized atomic, Wannier functions, you name it). So it is absolutely important
to report in papers which projector functions were used for the calculation of U. In particular, this is why one should be very careful when comparing U values from different papers. There are also other factors that influence the value of U (pseudopotentials,
oxidation state, functional, one-shot or self-consistent calculation). We have some papers in preparation on this topic, which hopefully would clarify a bit more these points. You can also check this web page:
<a href="http://theossrv1.epfl.ch/Main/DFTHubbard">http://theossrv1.epfl.ch/Main/DFTHubbard</a></p>
<p style="margin-bottom:0;margin-top:0"> </p>
<p style="margin-bottom:0;margin-top:0">Greetings,</p>
<p style="margin-bottom:0;margin-top:0">Iurii</p>
<p style="margin-bottom:0;margin-top:0"> </p>
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<div><font color="808080" face="'Times New Roman', Times, serif" size="3">--<br>
Dr. Iurii TIMROV<br>
Postdoctoral Researcher</font></div>
<div><font color="808080" face="'Times New Roman', Times, serif" size="3">STI - IMX
</font><font color="808080" face="'Times New Roman', Times, serif" size="3"></font><font color="808080" face="'Times New Roman', Times, serif" size="3">- THEOS</font><font color="808080" face="'Times New Roman', Times, serif" size="3"> and NCCR - MARVEL</font></div>
<div><font color="808080" face="'Times New Roman', Times, serif" size="3">Swiss Federal Institute of Technology Lausanne (EPFL</font><font color="808080" face="'Times New Roman', Times, serif" size="3">)</font></div>
<div><font color="808080" face="'Times New Roman', Times, serif" size="3">CH-1015 Lausanne, Switzerland<br>
+41 21 69 34 881</font></div>
<div><a href="http://people.epfl.ch/265334">http://people.epfl.ch/265334</a></div>
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<div><font color="#000000" face="Calibri, sans-serif" style="font-size:11pt"><strong>From:</strong> users <<a href="mailto:users-bounces@lists.quantum-espresso.org">users-bounces@lists.quantum-espresso.org</a>> on behalf of Lorenzo Paulatto <<a href="mailto:paulatz@gmail.com">paulatz@gmail.com</a>><br>
<strong>Sent:</strong> Wednesday, August 26, 2020 10:59:13 AM<br>
<strong>To:</strong> <a href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a><br>
<strong>Subject:</strong> Re: [QE-users] U calculation, different projection type</font>
<div> </div>
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<div><font size="2"><span style="font-size:10pt">> Is it expected behavior?<br>
<br>
Yes,<br>
kind regards<br>
<br>
> Thanks,<br>
> Sergey<br>
<br>
--<br>
Lorenzo Paulatto - Paris<br>
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