[QE-users] convergence NOT achieved using DFT+U
Iurii TIMROV
iurii.timrov at epfl.ch
Tue Feb 15 10:14:58 CET 2022
Dear William,
Here it is:
&control
calculation='scf'
restart_mode='from_scratch',
prefix='CoO2'
pseudo_dir = '../pseudo/'
outdir='./tmp'
/
&system
ibrav = 0,
nat = 3,
ntyp = 2,
ecutwfc = 90.0,
ecutrho = 1080.0,
nspin = 2,
starting_magnetization(1) = 0.5,
occupations = 'smearing'
smearing = 'mv'
degauss = 0.005,
vdw_corr = 'DFT-D3'
lda_plus_u = .true.,
lda_plus_u_kind = 0,
U_projection_type = 'ortho-atomic',
Hubbard_U(1) = 6.94
/
&electrons
diagonalization='david'
mixing_mode = 'local-TF'
mixing_beta = 0.1
conv_thr = 1.0d-15
/
ATOMIC_SPECIES
Co 58.933195 co_pbesol_v1.2.uspp.F.UPF
O 15.9994 O.pbesol-n-kjpaw_psl.0.1.UPF
ATOMIC_POSITIONS {crystal}
Co 0.0000000000 0.0000000000 0.0000000000
O 0.6666666667 0.3333333333 0.2393364144
O 0.3333333333 0.6666666667 0.7606635856
CELL_PARAMETERS {angstrom}
-1.495932918 -2.591031818 0.000000000
-1.495932918 2.591031818 0.000000000
0.000000000 0.000000000 -3.931228251
K_POINTS {automatic}
18 18 9 0 0 0
Greetings,
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: Antonio Pancho Ramirez <antoniopr1994 at hotmail.com>
Sent: Tuesday, February 15, 2022 9:43:35 AM
To: Iurii TIMROV; Quantum ESPRESSO users Forum
Subject: RE: convergence NOT achieved using DFT+U
Dear Iurii TIMROV,
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).
Best regards,
MSc William Pancho
Deparment of Materials Science
Bauman State University of Moscow, Russia, 105005
+7 9776217432
________________________________
De: users <users-bounces at lists.quantum-espresso.org> en nombre de Iurii TIMROV via users <users at lists.quantum-espresso.org>
Enviado: lunes, 14 de febrero de 2022 3:53
Para: users at lists.quantum-espresso.org <users at lists.quantum-espresso.org>
Asunto: Re: [QE-users] convergence NOT achieved using DFT+U
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-bounces at lists.quantum-espresso.org> on behalf of Antonio Pancho Ramirez <antoniopr1994 at hotmail.com>
Sent: Monday, February 14, 2022 10:27:42 AM
To: users at 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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