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<div class="elementToProof"><span style="letter-spacing: normal; font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(36, 36, 36); background-color: rgb(255, 255, 255); font-weight: 400;">Dear
Yin-Ying,</span></div>
<div class="elementToProof"><span style="letter-spacing: normal; font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 14.666667px; color: rgb(36, 36, 36); background-color: rgb(255, 255, 255); font-weight: 400;"><br>
</span></div>
<div class="elementToProof"><span style="letter-spacing: normal; font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 14.666667px; color: rgb(36, 36, 36); background-color: rgb(255, 255, 255); font-weight: 400;">> Why
is it not recommended or feasible to employ the Hubbard U parameters right from the first SCF calculation?</span></div>
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<br>
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It is feasible, you can do that. QE contains just one example with starting U=0.001, but you can use any value. </div>
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<br>
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<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">The
</span><span style="letter-spacing: normal; font-family: "Segoe UI", "Segoe UI Web (West European)", "Segoe UI", -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif; font-size: 14.666667px; color: rgb(36, 36, 36); background-color: rgb(255, 255, 255); font-weight: 400;">pmw.x</span><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> codes
reads the Kohn-Sham wavefunctions (which can be DFT or DFT+U), and then builds Wannier functions. Note that these are not maximally localized. In the future releases of QE there will be a possibility to use maximally localized Wannier functions from Wannier90
for DFT+U calculations (we are working on that).</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">HTH</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Iurii </span></div>
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<br>
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<div><span style="font-family: Cambria, Georgia, serif; font-size: 12pt; color: rgb(102, 102, 102);">Dr. Iurii TIMROV</span></div>
<div><span style="font-family: Cambria, Georgia, serif; font-size: 12pt; color: rgb(102, 102, 102);">Tenure-track scientist</span></div>
<div><span style="font-family: Cambria, Georgia, serif; font-size: 12pt; color: rgb(102, 102, 102);">Laboratory for Materials Simulations (LMS)</span></div>
<div><span style="font-family: Cambria, Georgia, serif; font-size: 12pt; color: rgb(102, 102, 102);">Paul Scherrer Institut (PSI)</span></div>
<div><span style="font-family: Cambria, Georgia, serif; font-size: 12pt; color: rgb(102, 102, 102);">CH-5232 Villigen, Switzerland</span></div>
<div><span style="font-family: Cambria, Georgia, serif; font-size: 12pt; color: rgb(102, 102, 102);">+41 56 310 62 14</span></div>
<div><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><a href="https://www.psi.ch/en/lms/people/iurii-timrov" target="_blank" rel="noopener noreferrer" data-auth="NotApplicable" data-linkindex="0">https://www.psi.ch/en/lms/people/iurii-timrov</a></span></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 Yin-Ying Ting <y.ting@fz-juelich.de><br>
<b>Sent:</b> Wednesday, January 24, 2024 17:09<br>
<b>To:</b> users@lists.quantum-espresso.org <users@lists.quantum-espresso.org><br>
<b>Subject:</b> [QE-users] Hubbard U Parameters in pmw.x</font>
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<div class="PlainText">Dear Quantum Espresso Community,<br>
<br>
I am currently working with the poormanwannier.x (pmw.x) as demonstrated<br>
in example05 of PP. In this example, the procedure begins with a<br>
self-consistent field (SCF) calculation without the incorporation of<br>
Wannier functions (wf) and with very small Hubbard parameters (around<br>
0.001). This is followed by the execution of pmw.x and a subsequent<br>
second SCF calculation, this time including Wannier functions and the<br>
Hubbard U parameters.<br>
<br>
My question pertains to the rationale behind this two-step SCF<br>
calculation approach, particularly concerning the Hubbard U parameters.<br>
Why is it not recommended or feasible to employ the Hubbard U parameters<br>
right from the first SCF calculation? Understanding the underlying<br>
reasoning for this process would greatly enhance my comprehension of the<br>
method and its applications.<br>
<br>
I appreciate any insights or explanations you can provide. Thank you for<br>
your time and assistance.<br>
<br>
Best regards,<br>
<br>
PhD student in Forschungszentrum Jülich<br>
<br>
Yin-Ying Ting<br>
<br>
--<br>
<br>
Forschungszentrum Jülich GmbH<br>
Institute of Energy and Climate Research<br>
Theory and Computation of Energy Materials (IEK-13)<br>
E-mail: y.ting@fz-juelich.de<br>
<br>
<br>
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