How to plot symmetric exciton wave function

Anything regarding the post-processing utility (e.g. excitonic wavefunction analysis) is dealt with in this forum.

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Daniele Varsano
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Re: How to plot symmetric exciton wave function

Post by Daniele Varsano » Mon Jul 04, 2022 10:28 am

Dear Xiangtian,

1) Yes, they can be compared. The exciton wavefunction is a conditional probability amplitude, ie the probability to find an electron in space having the hole fixed in space.
2) Yes correct, depending on the version you are using by default the max if the exc_wf is normalized to 1. This can be controlled by input by using the keyword "NormToOne".

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/

xtbu
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Re: How to plot symmetric exciton wave function

Post by xtbu » Mon Jul 04, 2022 12:25 pm

Dear Daniele,

Thank you for the reply. I got the point!
X. T. Bu
Beijing Institute of Technology, China

Reza_Reza
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The exciton spatial distribution

Post by Reza_Reza » Mon Mar 25, 2024 11:13 am

Hello,

I have performed calculations to compute the exciton oscillator strength, amplitude, and spatial distribution. However, I am struggling to interpret the output file in terms of identifying the strongest exciton and its corresponding "state" in the ypp_AMPL.in file.

I have attached the output and report files, along with the strength/energy figure.

Thank you,

Reza
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Reza - Postdoc
CNRS

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Daniele Varsano
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Re: How to plot symmetric exciton wave function

Post by Daniele Varsano » Tue Mar 26, 2024 7:14 pm

Dear Reza,

in the E_sorted file you have exciton index, energy and strength.
The strength is normalized to the largest one, in your case is the first one (index 1). The normalization factor is also reported.
Please note that you find at negative excitation energies, so it is possible that your calculation is not converged or you do not have taken into account qp correction correctly.
Once you have identified the index of the exciton you want to analyze, you can use ypp (ypp -a), select the index and look at its composition looking at the *weight output.

Please note that degenerate excitons are summed up, if you want to avoid this and analyse a single exciton you need to set:
Degen_Step=0 eV

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/

Reza_Reza
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Location: France

Re: How to plot symmetric exciton wave function

Post by Reza_Reza » Thu Mar 28, 2024 1:37 pm

Dear Daniele,

I calculated the exciton wave function based on the instruction. I have some problems analyzing it. 1. I cannot understand how I should determine the number of cells. Since I increased it, I observed the spreading of the exciton wave function (I attached the image), and I do not know if there is an optimum value for the number of cells.

2. Regarding the exciton index state (for instance, No. 1 in the E_stored output file), how is it possible to compute its contribution in different k-states?

3. In which input file can "ypp -a" be used?
excitons # [R] Excitonic properties
amplitude # [R] Amplitude
States= "1 - 1" # Index of the BS state(s)
BSQindex= 1 # Q-Index of the BS state(s)
Degen_Step= 0.010000 eV # Maximum energy separation of two degenerate states
and how can the contribution be analyzed?

I attached the related output file.

Best.

Reza
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Reza - Postdoc
CNRS

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