Hi Yambo Team,
Since I wanted to analyze the optical spectrum, I switched to e-h space, But the two spectra I got from both RPA and TDALDA are almost similar. And, TDALDA calculation is more time-consuming compared to RPA with similar parameters. Is there something wrong with my input? Here I attach the reports and input files for both calculations.
Thanks
Niranji
Questions about TDDFT and RPA outputs
Moderators: Davide Sangalli, andrea.ferretti, myrta gruning, andrea marini, Daniele Varsano, Conor Hogan
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Questions about TDDFT and RPA outputs
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Niranji Ekanayake
PhD Candidate
Department of Chemistry
Queen's University
Kingston, ON K7L 3N6
Canada
PhD Candidate
Department of Chemistry
Queen's University
Kingston, ON K7L 3N6
Canada
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OnlineDaniele Varsano
- Posts: 3872
- Joined: Tue Mar 17, 2009 2:23 pm
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Re: Questions about TDDFT and RPA outputs
Dear Niranji,
in bulk systems, alda approximations has very little effect wrt the RPA. It is more time-consuming as you have the alda extra term in the kernel.
What I find strange is that the spectra are practically identical to the IP spectrum, but I cannot spot anything wrong in the input file.
Have you already checked convergence with respect to the BSENGexx parameter?
Do you have the same effect when calculating the speturm in reciprocal space?
Best,
Daniele
in bulk systems, alda approximations has very little effect wrt the RPA. It is more time-consuming as you have the alda extra term in the kernel.
What I find strange is that the spectra are practically identical to the IP spectrum, but I cannot spot anything wrong in the input file.
Have you already checked convergence with respect to the BSENGexx parameter?
Do you have the same effect when calculating the speturm in reciprocal space?
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/
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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- Posts: 29
- Joined: Mon Oct 24, 2022 7:23 pm
Re: Questions about TDDFT and RPA outputs
Hi Daniele,
I have already checked the convergence with respect to the BSENGexx parameter. I have already attached the outputs for them. It does not show an effect of changing the parameter.
And I have calculated the spectrum for both ALDA and RPA. And they are not identical in G-space. The results are attached. What do you think? Thanks
Niranji
I have already checked the convergence with respect to the BSENGexx parameter. I have already attached the outputs for them. It does not show an effect of changing the parameter.
And I have calculated the spectrum for both ALDA and RPA. And they are not identical in G-space. The results are attached. What do you think? Thanks
Niranji
You do not have the required permissions to view the files attached to this post.
Niranji Ekanayake
PhD Candidate
Department of Chemistry
Queen's University
Kingston, ON K7L 3N6
Canada
PhD Candidate
Department of Chemistry
Queen's University
Kingston, ON K7L 3N6
Canada
-
OnlineDaniele Varsano
- Posts: 3872
- Joined: Tue Mar 17, 2009 2:23 pm
- Contact:
Re: Questions about TDDFT and RPA outputs
Dear Niranji,
i can see that also in G space local fields have not effect, RPA and IP are pretty the same. It seems that the system is rather homogeneous at least in the field direction (1,0,0).
The reason why G-space and transition space differ is because they are calculated with different number of bands, this can be seen also looking at the IP spectra.
Best,
Daniele
i can see that also in G space local fields have not effect, RPA and IP are pretty the same. It seems that the system is rather homogeneous at least in the field direction (1,0,0).
The reason why G-space and transition space differ is because they are calculated with different number of bands, this can be seen also looking at the IP spectra.
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/
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/