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<p>Dear Yuvam,</p>
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<div>> I wanted to know how do I know in what orbital how much U parameter I should provide.</div>
<div><br>
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<div>You can compute U from first principles using the hp.x code which is a part of Quantum ESPRESSO.<br>
</div>
<div><br>
</div>
<div>> In QE, there's only one option of Hubbard_U and not any orbital specific data. But in other programs like SIESTA, I had to put U and J value for each orbital, 3d and 4s in case of Cr.
<br>
</div>
<div><br>
</div>
<div>In QE there is a multichannel implementation for DFT+U, but it is still experimental. You can find some examples in
<span>q-e/test-suite/pw_lda+U</span>.<br>
</div>
<div><br>
</div>
<div>> Suppose I used U=5 in QE, how should I know what value should I use for SIESTA?
<br>
</div>
<div><br>
</div>
<div>The value of U is not <span>transferable</span> from one code to another. U depends on many factors (Hubbard manifold, pseudopotentials, functional, etc.). Have a look here:</div>
<div><a href="http://theossrv1.epfl.ch/Main/DFTHubbard" class="OWAAutoLink" id="LPlnk801673" previewremoved="true">http://theossrv1.epfl.ch/Main/DFTHubbard</a></div>
<div><br>
</div>
<div>> If I use U=5 for 3d in SIESTA, what should I use for 4s as it is also one of the outermost orbitals.
<br>
</div>
<p></p>
<p><br>
</p>
<p>Applying the U correction to s-type orbitals is <span>questionable</span>. Typically the U correction is applied to the orbitals of the d and f type. Sometimes people put U also on p-type orbitals, but there is also no general consensus about this.</p>
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<p>U=5 for 3d in SIESTA, does not mean that you will have U=5 for 3d in QE (see my comment above). Just compute it using hp.x.</p>
<p><br>
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<p>Greetings,</p>
<p>Iurii<br>
</p>
<p><br>
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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 Yuvam Bhateja <yuvamb16@gmail.com><br>
<b>Sent:</b> Thursday, October 29, 2020 1:58:44 PM<br>
<b>To:</b> Quantum ESPRESSO users Forum<br>
<b>Subject:</b> Re: [QE-users] DFT+U calculation and Hubbard_J0 parameter</font>
<div> </div>
</div>
<div>
<div dir="auto">Thank you very much for this valuable information.
<div dir="auto"><br>
</div>
<div dir="auto">I wanted to know how do I know in what orbital how much U parameter I should provide.</div>
<div dir="auto">In QE, there's only one option of Hubbard_U and not any orbital specific data. But in other programs like SIESTA, I had to put U and J value for each orbital, 3d and 4s in case of Cr. </div>
<div dir="auto">Suppose I used U=5 in QE, how should I know what value should I use for SIESTA? </div>
<div dir="auto">If I use U=5 for 3d in SIESTA, what should I use for 4s as it is also one of the outermost orbitals. </div>
<div dir="auto"><br>
</div>
<div dir="auto">Regards</div>
<div dir="auto">Yuvam</div>
<br>
<br>
<div class="gmail_quote" dir="auto">
<div dir="ltr" class="gmail_attr">On Wed, 28 Oct 2020, 5:03 pm Matteo Cococcioni, <<a href="mailto:matteo.cococcioni@unipv.it">matteo.cococcioni@unipv.it</a>> wrote:<br>
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<div>Dear Yuvam</div>
<div><br>
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<div>please see below.</div>
<div><br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">Il giorno mer 28 ott 2020 alle ore 10:58 Yuvam Bhateja <<a href="mailto:yuvamb16@gmail.com" target="_blank" rel="noreferrer">yuvamb16@gmail.com</a>> ha scritto:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="auto">Hello experts,
<div dir="auto"><br>
</div>
<div dir="auto">I have been using Quantum ESPRESSO for my project and now I wanted to include DFT+U in my calculation.</div>
<div dir="auto"><br>
</div>
<div dir="auto">I was using lda_plus_u_kind = 0 (which only uses Hubbard_U parameter) along with Hubbard_J0.</div>
<div dir="auto">For example-</div>
<div dir="auto"><br>
</div>
<div dir="auto">lda_plus_u_kind=0</div>
<div dir="auto">Hubbard_U(1)=5.0</div>
<div dir="auto">Hubbard_J0(1)=0.48</div>
<div dir="auto"><br>
</div>
<div dir="auto">Using the above configuration my system converged perfectly.</div>
<div dir="auto"><br>
</div>
<div dir="auto">I wanted to know if I am doing something wrong here? Will the value of Hubbard_J0 be even considered if I am using lda_plus_u_kind=0?</div>
</div>
</blockquote>
<div><br>
</div>
<div><br>
</div>
<div>why do you think there is something wrong? <br>
</div>
<div>In order to understand whether J0 makes any difference just try without it and compare the results.<br>
</div>
<div><br>
</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="auto">
<div dir="auto"><br>
</div>
<div dir="auto">I wished to replicate the results in other softwares like SIESTA which only uses rotationally invariant scheme (i.e., equivalent to lda_plus_u=1).</div>
<div dir="auto">Can I use values of U=5.0 and J=0.48 as mentioned above in other DFT codes?</div>
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</blockquote>
<div><br>
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<div>strictly speaking they are not the same thing (unless J = J0 = 0). here is the reference for J0: PHYSICAL REVIEW B 84, 115108 (2011). But I don't know how similar the results would be.</div>
<div><br>
</div>
<div>HTH</div>
<div><br>
</div>
<div>Matteo</div>
<div><br>
</div>
<div><br>
</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="auto">
<div dir="auto"><br>
</div>
<div dir="auto">Any suggestions would be very helpful.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Regards</div>
<div dir="auto">Yuvam Bhateja</div>
</div>
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<br>
-- <br>
<div dir="ltr">
<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div>Matteo Cococcioni<br>
</div>
<div>Department of Physics<br>
</div>
University of Pavia<br>
Via Bassi 6, I-27100 Pavia, Italy<br>
tel +39-0382-987485<br>
<div>e-mail <a href="mailto:lucio.andreani@unipv.it" target="_blank" rel="noreferrer">
matteo.cococcioni@unipv.it</a></div>
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Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu" rel="noreferrer noreferrer" target="_blank">www.max-centre.eu</a>)<br>
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