occupation numbers differ between QE and Yambo for half-metal materials

Concerns issues with computing quasiparticle corrections to the DFT eigenvalues - i.e., the self-energy within the GW approximation (-g n), or considering the Hartree-Fock exchange only (-x)

Moderators: Davide Sangalli, andrea.ferretti, myrta gruning, andrea marini, Daniele Varsano

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Dean
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Joined: Thu Oct 10, 2019 7:03 am

occupation numbers differ between QE and Yambo for half-metal materials

Post by Dean » Tue Dec 20, 2022 8:17 am

Dear Yambo developers and users,
I found different occupation numbers between QE and Yambo for half-metal materials.
From the out of QE, firstly, I found two fermi energies. And, for spin-up electrons., there is a gap; for spin-down, it is a metal. This material is a half-metal.
But, for yambo, it reported only one fermi level, as same as the fermi energy for spin-down electrons. Based on this fermi level, this material is a metal. And, the occupation numbers are changed and differ between QE and Yambo for spin-up electrons.
How can I solve this issue?
Thanks in advance.
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Dr. Yimin Ding
Soochow University, China.

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Daniele Varsano
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Re: occupation numbers differ between QE and Yambo for half-metal materials

Post by Daniele Varsano » Wed Dec 21, 2022 8:01 am

Dear Yimin,
you can try to repeat your setup setting in the input file:
ElecTemp=0.0 eV
and see if this solves the problem. before running the setup you need to delete the ./SAVE/ndb.* files

Best,

Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/

Dean
Posts: 98
Joined: Thu Oct 10, 2019 7:03 am

Re: occupation numbers differ between QE and Yambo for half-metal materials

Post by Dean » Wed Dec 21, 2022 1:10 pm

Dear Daniele,
Thanks for your reply.
I set "ElecTemp=0.0 eV" in input, but it did not change the occupations.
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Dr. Yimin Ding
Soochow University, China.

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Davide Sangalli
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Re: occupation numbers differ between QE and Yambo for half-metal materials

Post by Davide Sangalli » Fri Dec 23, 2022 4:56 pm

Dear Yimin,
you are probably running qe using

Code: Select all

fixed_magetization
or

Code: Select all

tot_magnetization
fixed_occupations
This is not allowed by yambo. You should set

Code: Select all

starting_magnetization
instead.
We will add a barrier with an error message in the future releases.

Best,
D.
Davide Sangalli, PhD
CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit) and MaX Centre
https://sites.google.com/view/davidesangalli
http://www.max-centre.eu/

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