Spin-polarized band interpolation

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kle2797
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Joined: Mon Jul 12, 2021 3:21 pm

Spin-polarized band interpolation

Post by kle2797 » Fri Mar 25, 2022 1:11 am

Dear Developers,

I used ypp to interpolate the bands from QE calculation for a spin polarized system and got some weird output compared to the band structure I got from QE's `bands.x` and `plotbands.x`.
fig.pdf
What I did was simply generate the SAVE database using `p2y` from a nscf calculation, and then used 'ypp -s b' to get the input file. The spin up channel seems good, but the spin down is quite off. So I wonder whether I generate the SAVE database incorrectly which may affect my other calculations.

I also attached my nscf and ypp input file here for you inspection.

Thank you!
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Khoa Le
PhD Candidate
California Institute of Technology

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Davide Sangalli
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Re: Spin-polarized band interpolation

Post by Davide Sangalli » Fri Mar 25, 2022 9:08 am

Dear Khoa,

the issue is that there is a missing conversion factor in the values of the spin down channel.
Just multiply the energies by 27.2114 (the conversion factor from Hartree to eV) and you should get the correct value.

Best,
D.

P.S.: this could give problems

Code: Select all

%BANDS_kpts                      # K points of the bands circuit
0.000000  |0.000000  |0.000000  |  !G
0.500000  |0.000000  |0.000000  |  !M
0.333333  |0.333333  |0.000000  |  !K
0.000000  |0.000000  |0.000000  |  !G
%
can you try changing it to

Code: Select all

%BANDS_kpts                      # K points of the bands circuit
0.000000  |0.000000  |0.000000  |  #G
0.500000  |0.000000  |0.000000  |  #M
0.333333  |0.333333  |0.000000  |  #K
0.000000  |0.000000  |0.000000  |  #G
%
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/

kle2797
Posts: 14
Joined: Mon Jul 12, 2021 3:21 pm

Re: Spin-polarized band interpolation

Post by kle2797 » Fri Mar 25, 2022 3:34 pm

Davide Sangalli wrote: Fri Mar 25, 2022 9:08 am Dear Khoa,

the issue is that there is a missing conversion factor in the values of the spin down channel.
Just multiply the energies by 27.2114 (the conversion factor from Hartree to eV) and you should get the correct value.

Best,
D.

P.S.: this could give problems

Code: Select all

%BANDS_kpts                      # K points of the bands circuit
0.000000  |0.000000  |0.000000  |  !G
0.500000  |0.000000  |0.000000  |  !M
0.333333  |0.333333  |0.000000  |  !K
0.000000  |0.000000  |0.000000  |  !G
%
can you try changing it to

Code: Select all

%BANDS_kpts                      # K points of the bands circuit
0.000000  |0.000000  |0.000000  |  #G
0.500000  |0.000000  |0.000000  |  #M
0.333333  |0.333333  |0.000000  |  #K
0.000000  |0.000000  |0.000000  |  #G
%
Hi Davide,

Thank you for your reply. Multiply by the conversion factor does give the good bands. However, I tried your suggestion to the ypp input, but it did not fix it.

It seems to be just about 'ypp' interpolation, so do you think the database is good to do GW-BSE for the spin-flip channel?

Best,
Khoa Le
PhD Candidate
California Institute of Technology

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Daniele Varsano
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Re: Spin-polarized band interpolation

Post by Daniele Varsano » Tue Mar 29, 2022 9:15 pm

Dear Khoa Le

the missing factor is not related to the input file.

Code: Select all

so do you think the database is good to do GW-BSE for the spin-flip channel?
You can safely proceed with GW/BSE calculations, however, it is not clear to me what do you mean by spin-flip channel.

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/

kle2797
Posts: 14
Joined: Mon Jul 12, 2021 3:21 pm

Re: Spin-polarized band interpolation

Post by kle2797 » Mon Apr 04, 2022 6:32 pm

Daniele Varsano wrote: Tue Mar 29, 2022 9:15 pm
You can safely proceed with GW/BSE calculations, however, it is not clear to me what do you mean by spin-flip channel.
Hi Daniele,

Thank you for the reply and my apologize for the late respond.
What I mean is the calculation of magnon using BSEprop = "magn". So can I assume it is still safe in this case then?

Khoa
Khoa Le
PhD Candidate
California Institute of Technology

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Daniele Varsano
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Re: Spin-polarized band interpolation

Post by Daniele Varsano » Tue Apr 05, 2022 7:28 am

Dear Khoa,

most probably yes, even if I'm not an expert in this kind of calculation.

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/

kle2797
Posts: 14
Joined: Mon Jul 12, 2021 3:21 pm

Re: Spin-polarized band interpolation

Post by kle2797 » Tue Apr 05, 2022 7:03 pm

Daniele Varsano wrote: Tue Apr 05, 2022 7:28 am Dear Khoa,

most probably yes, even if I'm not an expert in this kind of calculation.

Best,
Daniele
Thank you for your help!
Khoa Le
PhD Candidate
California Institute of Technology

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