<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<style type="text/css" style="display:none;"><!-- P {margin-top:0;margin-bottom:0;} --></style>
<div id="divtagdefaultwrapper" style="font-size:12pt;color:#000000;font-family:Calibri,Helvetica,sans-serif;" dir="ltr">
<p>Dear William,</p>
<p><br>
</p>
<p>Do not forget to indicate your affiliation when posting on this forum.</p>
<p><br>
</p>
<p><span>> Hubbard_U(1) = 3.4 (this value I took from a paper: Aykol, M., Kim, S., & Wolverton, C. (2015).</span><br>
</p>
<p><br>
</p>
<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="OWAAutoLink" id="LPlnk870160" previewremoved="true">https://aip.scitation.org/doi/10.1063/1.4945608</a></p>
<p><br>
</p>
<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="OWAAutoLink" id="LPlnk335009" previewremoved="true">
http://theossrv1.epfl.ch/Main/DFTHubbard</a></p>
<p><br>
</p>
<p><span>> conv_thr = 1e-5 </span><br>
</p>
<p><br>
</p>
<p>This is too large. You should use 1e-10 -- 1e-15</p>
<p><br>
</p>
<p><span>> diagonalization = 'cg'</span><br>
</p>
<p><br>
</p>
<p>Better use "davidson"</p>
<p><br>
</p>
<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.
<br>
</p>
<p><br>
</p>
<p>HTH</p>
<p><br>
</p>
<p>Iurii<br>
</p>
<p><br>
</p>
<div id="Signature">
<div id="divtagdefaultwrapper" dir="ltr" style="font-size: 12pt; color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif, "EmojiFont", "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols;">
<div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0">
<div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0">
<font size="3" face="'Times New Roman', Times, serif" color="808080">--<br>
<span style="font-family:Cambria,Georgia,serif">Dr. Iurii TIMROV</span><br>
<span style="font-family:Cambria,Georgia,serif">Senior Research Scientist</span></font></div>
<div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0">
<font size="3" face="'Times New Roman', Times, serif" color="808080"><span style="font-family:Cambria,Georgia,serif">Theory and Simulation of Materials (THEOS)</span></font></div>
<div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0">
<span style="font-size:12pt; color:rgb(128,128,128); font-family:Cambria,Georgia,serif">Swiss Federal Institute of Technology Lausanne (EPFL</span><font style="font-size:12pt; color:rgb(128,128,128); font-family:"Times New Roman",Times,serif" color="808080"><font face="'Times New Roman', Times, serif"><span style="font-family:Cambria,Georgia,serif">)</span></font></font><br>
</div>
<span style="font-family:Cambria,Georgia,serif"></span><font color="808080"></font><span style="font-family:Cambria,Georgia,serif"></span>
<div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0">
<span style="font-family:Cambria,Georgia,serif"></span><font size="3" face="'Times New Roman', Times, serif" color="808080"><span style="font-family:Cambria,Georgia,serif">CH-1015 Lausanne, Switzerland</span><br>
<span style="font-family:Cambria,Georgia,serif">+41 21 69 34 881</span></font></div>
<span style="font-family:Cambria,Georgia,serif"></span>
<div name="divtagdefaultwrapper" style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:; margin:0">
<span style="font-family:Cambria,Georgia,serif"></span><a href="http://people.epfl.ch/265334" tabindex="0" id="LPNoLP"><span style="font-family:Cambria,Georgia,serif">http://people.epfl.ch/265334</span></a><br>
</div>
</div>
</div>
</div>
</div>
<hr style="display:inline-block;width:98%" tabindex="-1">
<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 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>
<div> </div>
</div>
<div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Dear Members,</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
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.
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
</div>
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
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<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>
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I had already tried to change the conv_thr, diagonalization, etc. as it is show below
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
conv_thr = 1e-5
<div> diagonalization = 'cg'</div>
<div> mixing_beta = 0.3</div>
mixing_mode = 'local-TF'<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
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>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Best regards</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
William Pancho <br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
</div>
</body>
</html>