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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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