Dear William,
Do not forget to indicate your affiliation when posting on this forum. > Hubbard_U(1) = 3.4 (this value I took from a paper: Aykol, M., Kim, S., & > Wolverton, C. (2015). This is not correct. They used VASP which uses different Hubbard projectors, while you are using QE with "atomic" Hubbard projectors. Check this paper: https://aip.scitation.org/doi/10.1063/1.4945608 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: http://theossrv1.epfl.ch/Main/DFTHubbard > conv_thr = 1e-5 This is too large. You should use 1e-10 -- 1e-15 > diagonalization = 'cg' Better use "davidson" 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. HTH Iurii -- Dr. Iurii TIMROV Senior Research Scientist Theory and Simulation of Materials (THEOS) Swiss Federal Institute of Technology Lausanne (EPFL) CH-1015 Lausanne, Switzerland +41 21 69 34 881 http://people.epfl.ch/265334 ________________________________ From: users <users-boun...@lists.quantum-espresso.org> on behalf of Antonio Pancho Ramirez <antoniopr1...@hotmail.com> Sent: Monday, February 14, 2022 10:27:42 AM To: users@lists.quantum-espresso.org Subject: [QE-users] convergence NOT achieved using DFT+U Dear Members, 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. The Journal of Physical Chemistry C, 119(33), 19053-19058.). I have performed all the calculations using QE v.6.7MaX. 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 &CONTROL calculation = 'scf' outdir='tmp', prefix = 'CoO_U' pseudo_dir = '.', tprnfor = .true. verbosity = 'high' / &SYSTEM ecutrho = 800 ecutwfc = 70 ibrav = 0 nat = 3 ntyp = 2 occupations='smearing', smearing='gauss', degauss=0.015, nspin=2 starting_magnetization(1) = 0.1 lda_plus_u = .true., Hubbard_U(1) = 3.4 vdw_corr='grimme-d3' / &ELECTRONS / ATOMIC_SPECIES Co 58.933194 co_pbe_v1.2.uspp.F.UPF O 15.999 o_pbe_v1.2.uspp.F.UPF CELL_PARAMETERS angstrom 2.8413505554 0.0000000000 0.0000000000 1.4206751885 2.4606823642 0.0000000000 1.4206754552 0.8202267469 4.7143528794 ATOMIC_POSITIONS crystal Co 0.0000000000 0.0000000000 0.0000000000 O 0.7396634820 0.7396634820 0.7810095550 O 0.2603365180 0.2603365180 0.2189904750 K_POINTS automatic 6 6 6 0 0 0 I had already tried to change the conv_thr, diagonalization, etc. as it is show below conv_thr = 1e-5 diagonalization = 'cg' mixing_beta = 0.3 mixing_mode = 'local-TF' 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. Best regards William Pancho
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