Momentum dependent Independent-particle-approximation

Deals with issues related to computation of optical spectra in reciprocal space: RPA, TDDFT, local field effects.

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

Fadil
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Re: Momentum dependent Independent-particle-approximation

Post by Fadil » Tue Sep 27, 2022 9:30 am

I see, thank you!
Dr. Fadıl İYİKANAT
ICFO-The Institute of Photonic Sciences
Barcelona-SPAIN

Fadil
Posts: 56
Joined: Sun May 24, 2020 1:56 pm

Re: Momentum dependent Independent-particle-approximation

Post by Fadil » Sun Dec 11, 2022 2:57 pm

Dear all,

Do we need to run momentum-dependent RPA or BSE calculations in the full Brillouin zone instead of IBZ?
And are the q-vectors calculated only for the first Brillouin zone?

Best
Dr. Fadıl İYİKANAT
ICFO-The Institute of Photonic Sciences
Barcelona-SPAIN

Fadil
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Re: Momentum dependent Independent-particle-approximation

Post by Fadil » Fri Dec 16, 2022 11:42 am

Dear all,

You can find dielectric functions for q-dependent ipa and bse calculations with or without taking into account the symmetries in the system.
After calculating the ground state I switched-off the symmetries with ypp.
It seems that ipa for a specific momentum is giving the same results with or without symmetry while bse is giving very different spectra.
Does anyone knows what is wrong?

Best
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Dr. Fadıl İYİKANAT
ICFO-The Institute of Photonic Sciences
Barcelona-SPAIN

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Daniele Varsano
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Re: Momentum dependent Independent-particle-approximation

Post by Daniele Varsano » Sat Dec 17, 2022 8:42 am

Dear Fadıl,

actually, we should investigate what's going wrong here and from the output file only it is not possible to understand.

Can you post the report and input files for the two calculations? I do not understand how you have the same dimension of the excitonic matrix independently of the usage of the symmetries.

In case we would need to reproduce your problem, it would be preferable if you could update to the newest release of the code and repeat the 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/

Fadil
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Re: Momentum dependent Independent-particle-approximation

Post by Fadil » Mon Dec 19, 2022 1:02 pm

Hi Daniele,

Thank you for the response. Unfortunately, I am having some issues to install the latest version of the code to our cluster.
But I did the similar calculations in an another version of the code (5.0.3) and they gave the same issue.
You can find input, output and report files (with symmetry and without symmetry (labeled as no_sym) ) in the attachment.

Best regards
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Dr. Fadıl İYİKANAT
ICFO-The Institute of Photonic Sciences
Barcelona-SPAIN

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Daniele Varsano
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Re: Momentum dependent Independent-particle-approximation

Post by Daniele Varsano » Wed Dec 21, 2022 8:14 am

Dear Fadil,
Thanks for reporting, we will investigate the issue.
It is possible we will have to reproduce your problem, in this case I will ask you QE input and pseudo. It would be desirable to have a minimal (low parameter, fast calculation) example showing the problem.

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/

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Davide Sangalli
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Re: Momentum dependent Independent-particle-approximation

Post by Davide Sangalli » Wed Dec 21, 2022 9:20 am

Dear Fadil,
this is a known issue for simulations with SOC.
Indeed, in the gpl, finite-q bse with SOC has been switched off.

There is a branch which you can use where this issue has been fixed.
However the bse implementation there is numerically a bit more demanding.
https://github.com/yambo-code/yambo/tre ... nite-q-dir

The issue exists only in presence of SOC.

Best,
D
Davide Sangalli, PhD
CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit) and MaX Centre
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Fadil
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Re: Momentum dependent Independent-particle-approximation

Post by Fadil » Sat Dec 24, 2022 1:18 pm

Dear Daniele,

Since this is a known issue I assume there is no need to reproduce the problem otherwise please let me know.

Dear Davide,

Thank you for the clarification.
Then, SOC-included finite-q bse calculations by considering IBZ or full-BZ (switching-off symmetries by ypp) have problems in both?

Best
Dr. Fadıl İYİKANAT
ICFO-The Institute of Photonic Sciences
Barcelona-SPAIN

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Davide Sangalli
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Re: Momentum dependent Independent-particle-approximation

Post by Davide Sangalli » Sat Dec 24, 2022 9:49 pm

Yeah, both simulations with and without symmetries have issues. My suggestion is to check the branch with the fix.

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/

Fadil
Posts: 56
Joined: Sun May 24, 2020 1:56 pm

Re: Momentum dependent Independent-particle-approximation

Post by Fadil » Sat Dec 24, 2022 9:57 pm

Thank you!
Dr. Fadıl İYİKANAT
ICFO-The Institute of Photonic Sciences
Barcelona-SPAIN

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