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Dear Iurii TIMROV,</div>
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I really appreciate your help. I will check all the given suggestion. When it comes to the structure I used VESTA to vizualize, and everything seems good using this unit cell. I have alredy check the structure data base, and you right, there are some differences.
if it is possible I would like to kindly request your input file to compare (mainly the structure).
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Best regards,</div>
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MSc William Pancho</div>
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Deparment of Materials Science <br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>De:</b> users <users-bounces@lists.quantum-espresso.org> en nombre de Iurii TIMROV via users <users@lists.quantum-espresso.org><br>
<b>Enviado:</b> lunes, 14 de febrero de 2022 3:53<br>
<b>Para:</b> users@lists.quantum-espresso.org <users@lists.quantum-espresso.org><br>
<b>Asunto:</b> Re: [QE-users] convergence NOT achieved using DFT+U</font>
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<p>Dear William,</p>
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<p>Do not forget to indicate your affiliation when posting on this forum.</p>
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<p><span>> Hubbard_U(1) = 3.4 (this value I took from a paper: Aykol, M., Kim, S., & Wolverton, C. (2015).</span><br>
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<p>This is not correct. They used VASP which uses different Hubbard projectors, while you are using QE with "atomic" Hubbard projectors. Check this paper: <a href="https://aip.scitation.org/doi/10.1063/1.4945608" class="x_OWAAutoLink" id="LPlnk870160">https://aip.scitation.org/doi/10.1063/1.4945608</a></p>
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<p>I recommend to compute U using the HP code of QE. Also use 'ortho-atomic' instead of 'atomic' projectors, because the former are more accurate:
<a href="http://theossrv1.epfl.ch/Main/DFTHubbard" class="x_OWAAutoLink" id="LPlnk335009">
http://theossrv1.epfl.ch/Main/DFTHubbard</a></p>
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<p><span>> conv_thr = 1e-5 </span><br>
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<p>This is too large. You should use 1e-10 -- 1e-15</p>
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<p><span>> diagonalization = 'cg'</span><br>
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<p>Better use "davidson"</p>
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<p>How did you obtain your structure? Did you visualize it and check that all is correct? In the past I also modeled CoO2 and it converged fine (my input looks different from yours). Check available crystal structure databases and search for CoO2 there.
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<p>HTH</p>
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<p>Iurii<br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">--<br>
<span style="font-family:Cambria,Georgia,serif">Dr. Iurii TIMROV</span><br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> users <users-bounces@lists.quantum-espresso.org> on behalf of Antonio Pancho Ramirez <antoniopr1994@hotmail.com><br>
<b>Sent:</b> Monday, February 14, 2022 10:27:42 AM<br>
<b>To:</b> users@lists.quantum-espresso.org<br>
<b>Subject:</b> [QE-users] convergence NOT achieved using DFT+U</font>
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Dear Members,</div>
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I have been working with LiCoO2 and CoO2, performing DFT calculation to determine the intercalation potential. However, when it comes to CoO2 after adding the Hubbard correction (DFT+U) convergences cannot be reached. I have just added two lines to the
original input file: lda_plus_u = .true. and Hubbard_U(1) = 3.4 (this value I took from a paper: Aykol, M., Kim, S., & Wolverton, C. (2015). Van der Waals interactions in layered lithium cobalt oxides.
<i>The Journal of Physical Chemistry C</i>, <i>119</i>(33), 19053-19058.). I have performed all the calculations using QE v.6.7MaX.
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Kindly have a look at the input file and suggest why its so hard to converge this relatively simple system after adding the U correction
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<pre>&CONTROL<div> calculation = 'scf'</div><div> outdir='tmp',</div><div> prefix = 'CoO_U'</div><div> pseudo_dir = '.',</div><div> tprnfor = .true.</div><div> verbosity = 'high'</div><div>/</div><div>&SYSTEM</div><div> ecutrho = 800</div><div> ecutwfc = 70</div><div> ibrav = 0</div><div> nat = 3</div><div> ntyp = 2</div><div> occupations='smearing', smearing='gauss', degauss=0.015,</div><div> nspin=2</div><div> starting_magnetization(1) = 0.1</div><div> lda_plus_u = .true.,</div><div> Hubbard_U(1) = 3.4</div><div> vdw_corr='grimme-d3'</div><div><br></div><div>/</div><div>&ELECTRONS</div><div>/</div><div>ATOMIC_SPECIES</div><div>Co 58.933194 co_pbe_v1.2.uspp.F.UPF</div><div>O 15.999 o_pbe_v1.2.uspp.F.UPF</div><div>CELL_PARAMETERS angstrom</div><div> 2.8413505554 0.0000000000 0.0000000000</div><div> 1.4206751885 2.4606823642 0.0000000000</div><div> 1.4206754552 0.8202267469 4.7143528794</div><div>ATOMIC_POSITIONS crystal </div><div>Co 0.0000000000 0.0000000000 0.0000000000 </div><div>O 0.7396634820 0.7396634820 0.7810095550 </div><div>O 0.2603365180 0.2603365180 0.2189904750 </div><div>K_POINTS automatic</div>6 6 6 0 0 0<br></pre>
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I had already tried to change the conv_thr, diagonalization, etc. as it is show below
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conv_thr = 1e-5
<div> diagonalization = 'cg'</div>
<div> mixing_beta = 0.3</div>
mixing_mode = 'local-TF'<br>
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But noting seems to work. I believe that the problem could be related to the magnetization (hing and low spin state). Maybe to force the system to low spin state but I not sure how to do that or if the problem is connected with that. Additionally, I use gbrv
pseudopotential for these calculation. <br>
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Best regards</div>
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William Pancho <br>
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