BSE spectra showing very low eps values

Deals with issues related to computation of optical spectra, solving the Bethe-Salpeter equation.

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Ponnappa
Posts: 10
Joined: Sat Sep 07, 2024 7:26 pm

BSE spectra showing very low eps values

Post by Ponnappa » Fri Oct 04, 2024 6:51 am

Dear Yambo Developers and users,
I was trying the BSE spectra for a 2D semiconducting material. I have obtained the spectra but have two concerns ragarding the same.

1) The eps values which are obtained are very low .

2) Inspite of being a semiconductor the spectra starts from non zero value.

I donot understand the reason behind this. I am attaching the input files of the 3 steps which I used (and the K points for BSE calculation 42*42*1) and the eps spectra . Looking forward for the response. Thank you in Advance.

Regards,
Ponnappa K. P.
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Ponnappa K. P.
Phd Student
Harish Chadra Research Institute, India

Ponnappa
Posts: 10
Joined: Sat Sep 07, 2024 7:26 pm

Re: BSE spectra showing very low eps values

Post by Ponnappa » Fri Oct 04, 2024 6:53 am

I have attached the eps spectra.

Regars,
Ponnappa
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Ponnappa K. P.
Phd Student
Harish Chadra Research Institute, India

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Daniele Varsano
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Joined: Tue Mar 17, 2009 2:23 pm
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Re: BSE spectra showing very low eps values

Post by Daniele Varsano » Fri Oct 04, 2024 7:06 am

Dear Ponappa,
1) The eps values which are obtained are very low:
please have a look at the FAQ:
https://www.yambo-code.eu/learn/#FAQs

2) Inspite of being a semiconductor the spectra starts from non zero value:
This is the effect of the Lorentzian smearing, if you reduce it you the non zero absorption at zero energy will disappear.

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/

Ponnappa
Posts: 10
Joined: Sat Sep 07, 2024 7:26 pm

Re: BSE spectra showing very low eps values

Post by Ponnappa » Sat Oct 05, 2024 5:41 pm

Dear Daniele Varsano,
Thank you, I could fix the problem with your suggestion.
Ponnappa K. P.
Phd Student
Harish Chadra Research Institute, India

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