[QE-users] SCf convergence for antiferromagnetic insulator

[Iurii TIMROV]

Try to use the Quantum ESPRESSO input generator: https://www.materialscloud.org/work/tools/qeinputgenerator


In your input you have:

    occupations               = "fixed"
    smearing                  = "gaussian"
You need to decide what do you want: either use smearing (occupations="smearing" and specify the smearing type ("smearing" keyword) and the value of the broadening ("degauss" keyword)) or use fixed occupations (occupations = "fixed").


You can try to use mixing_mode='local-TF'.


You have: estimated scf accuracy    <       0.05813498 Ry after 100 iterations. This is very far from the "good" convergence (say ~10^{-10} Ry), so likely there is something wrong with your structure and/or the magnetization that you impose. Check carefully these things. Also you can try to converge the structure without the Hubbard U correction.


Greetings,

Iurii


--
Dr. Iurii TIMROV
Postdoctoral Researcher
STI - IMX - THEOS and NCCR - MARVEL
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 Diship Srivastava <dishipsrivastava at gmail.com>
Sent: Wednesday, December 2, 2020 12:29:38 PM
To: Quantum ESPRESSO users Forum
Subject: Re: [QE-users] SCf convergence for antiferromagnetic insulator


[https://drive-thirdparty.googleusercontent.com/16/type/application/vnd.google-apps.folder] quantum_espresso<https://drive.google.com/drive/folders/1qqa1dXQaPi20Osve8sXGFjo7RNcn_3HS>
Thanks for prompt reply.
Please find my input and output file in google drive attachment.


On Wed, 2 Dec 2020 at 16:43, Iurii TIMROV <iurii.timrov at epfl.ch<mailto:iurii.timrov at epfl.ch>> wrote:

Dear Diship Srivastava,


> My questions is this : Can I use first two steps of above mentioned
> example with previously calculated hubbard parameter values inserted
> to calculate scf energy ie  first calculate scf energy with occupation
> = smearing (ie fake magnetic metal) and .then use occupations = fixed
> and total magnetization = 0 along with the wavefunctions and the
> potential obtained in the previous step to get the scf energy.
>  Any other suggestions will also be most helpful.


Yes, you can. If you continue doing this loop (two PWscf calculations + recompute Hubbard parameters using DFPT) you will obtain self-consistent Hubbard parameters: https://arxiv.org/abs/2011.03271


> ...my system failed to converge


If you share your input and output files via the Google Drive, we can have a look what is wrong and try to fix this.


Greetings,

Iurii


--
Dr. Iurii TIMROV
Postdoctoral Researcher
STI - IMX - THEOS and NCCR - MARVEL
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<mailto:users-bounces at lists.quantum-espresso.org>> on behalf of Diship Srivastava <dishipsrivastava at gmail.com<mailto:dishipsrivastava at gmail.com>>
Sent: Wednesday, December 2, 2020 11:56:27 AM
To: users at lists.quantum-espresso.org<mailto:users at lists.quantum-espresso.org>
Subject: [QE-users] SCf convergence for antiferromagnetic insulator

Hi,
I had previously used procedure used in
https://gitlab.com/QEF/q-e/-/tree/3ec392ecee8a83958789d31be5737adac07974ba/HP/examples/example02
to calculate hubbard parameter for my antiferromagnetic insulator
system which matches with previously reported values. The scf
calculation with occupations = fixed and total magnetization = 0 (as
suggested in
https://www.quantum-espresso.org/Doc/INPUT_PW.html#idm1129)  my system
failed to converge. I tried usual methods like changing mixing beta
values etc but it also failed.

My questions is this : Can I use first two steps of above mentioned
example with previously calculated hubbard parameter values inserted
to calculate scf energy ie  first calculate scf energy with occupation
= smearing (ie fake magnetic metal) and .then use occupations = fixed
and total magnetization = 0 along with the wavefunctions and the
potential obtained in the previous step to get the scf energy.
 Any other suggestions will also be most helpful.

--
Diship Srivastava
JRF
Department of Chemistry
IIT(ISM) - Dhanbad
India
_______________________________________________
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_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu>)
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--
Diship Srivastava
JRF
Department of Chemistry
IIT(ISM) - Dhanbad
India
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