Weight of excitation

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xtbu
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Joined: Sat Jul 20, 2019 4:15 am

Weight of excitation

Post by xtbu » Thu Dec 19, 2019 2:19 am

Dear developers,
I am wondering about the wieght in ypp output inducing from ypp -e a as:
# Band_V Band_C K ibz Symm. Weight Energy
#
32.0000 33.0000 12.0000 6.0000 0.1080 1.4859
32.0000 33.0000 12.0000 5.0000 0.1080 1.4859
32.0000 33.0000 12.0000 4.0000 0.1080 1.4859
31.00 34.00 12.0 6.000 0.6421E-1 1.506
31.00 34.00 12.0 5.000 0.6419E-1 1.506
31.00 34.00 12.0 4.000 0.6419E-1 1.506
If I want to konw the contributions of the trasition, like 32-33 as above, I need to count the contribution 0.108x3 or just 0.108?
An other thing is the total weight are not equal 1, far less than 1. Why?

Thanks!

xt Bu
Xiangtian Bu, M.S.
School of Physical Science and Technology, Inner Mongolia University, Hohhot, P. R. China

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Davide Sangalli
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Re: Weight of excitation

Post by Davide Sangalli » Thu Dec 19, 2019 3:18 pm

Dear Xiangtian Bu,
you should count 0.108x3

The total weight is not 1 because, in the output are reported only the weights of the most relevant transitions.
There is a default threshold at 5% of the total weight. You can lower the threshold via the variable "Weight_treshold"

Best,
D.
Davide Sangalli, PhD
CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit) and MaX Centre
http://www.ism.cnr.it/en/davide-sangalli-cv/
http://www.max-centre.eu/

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Daniele Varsano
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Re: Weight of excitation

Post by Daniele Varsano » Thu Dec 19, 2019 6:28 pm

Dear Xiangtian Bu,

the variable controlling the threshold of the transition printed in the output is "MinWeight" that will be substituted with "Weight_treshold" in the next release.
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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claudio
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Re: Weight of excitation

Post by claudio » Fri Dec 20, 2019 9:36 am

Dear Xiangtian Bu,

probably the name Weight is not so correct, it should be better to call it "percentage contribution" to the exciton

best
Claudio
Claudio Attaccalite
[CNRS/ Aix-Marseille Université/ CINaM laborarory / TSN department
Campus de Luminy – Case 913
13288 MARSEILLE Cedex 09
web site: http://www.attaccalite.com
Freely download scientific books from: http://www.freescience.info

xtbu
Posts: 11
Joined: Sat Jul 20, 2019 4:15 am

Re: Weight of excitation

Post by xtbu » Mon Apr 27, 2020 10:38 am

Thanks, Davide, Daniele and Claudio,
So is the weight stands for |A_eh|^2?Where the A is the prefactor of |S>?
Thanks!

Xiangtian
Xiangtian Bu, M.S.
School of Physical Science and Technology, Inner Mongolia University, Hohhot, P. R. China

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Daniele Varsano
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Re: Weight of excitation

Post by Daniele Varsano » Mon Apr 27, 2020 11:22 am

Dear Xiangtian,

yes, the weight is defined as you indicated.

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
Posts: 11
Joined: Sat Jul 20, 2019 4:15 am

Re: Weight of excitation

Post by xtbu » Thu May 21, 2020 10:39 am

Dear all,
I got the exciton dipoles as described here"http://www.yambo-code.org/wiki/index.ph ... e_excitons".
And it is |A_eh<e|D|h>|, and whose square is proportional to oscillator strength. And I obtained the dipoles through Residuals as decroced here as :
Res=8pi/(q^2\Omega Nq)*|BS_R|^2. But why the two method has a different value of dipoles? I think |A_eh<e|D|h>|^2 should be equal as |BS_R|^2 here.

Thanks!

Xiang tiang
Xiangtian Bu, M.S.
School of Physical Science and Technology, Inner Mongolia University, Hohhot, P. R. China

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Daniele Varsano
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Re: Weight of excitation

Post by Daniele Varsano » Thu May 21, 2020 11:07 am

Dear Xiang,

I'm not sure I've understood your question,
I think |A_eh<e|D|h>|^2 should be equal as |BS_R|^2 here.
This is correct, these are the weighted transition dipoles, and the residuals are defined as you say, by multiplying them by a prefactor.
Maybe can be useful to look at this thread.

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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