LRC

Deals with issues related to computation of optical spectra, in RPA (-o c) or by solving the Bethe-Salpeter equation (-o b). Includes local field effects, excitons, etc.

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

samaneh
Posts: 165
Joined: Tue Jan 21, 2014 9:03 am

LRC

Post by samaneh » Tue Jan 19, 2016 7:32 am

Dear Developers,
As I asked you before in my previous post
"viewtopic.php?f=13&t=1117"
I use this way to do tddft calculations with yambo-3.4.1:
1- p2y
2- yambo -i
3- yambo
3- yambo -o c -k lrc -V all
4- yambo
but I do not know why it does not work?!
it means that the generated input file is just like the input for RPA calculation
with the only difference that it has "Chimod= "LRC" instead of "Chimod= "HARTREE"
so I added the alpha, beta and tddft parameters manually
but again there are no mentioned parameters in the output!!!
and the data is similar to the RPA data with a very little difference!!!
I attached the input and output files.
Thank you.
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S. Ataei, PhD student at University of Tehran, Iran.

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Daniele Varsano
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Re: LRC

Post by Daniele Varsano » Tue Jan 19, 2016 10:10 am

Dear samaneh,
I will have a look as soon as I can. Anyway last time I was not able to reproduce your problem. Moreover, as this discussion was already started why open a new 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/

samaneh
Posts: 165
Joined: Tue Jan 21, 2014 9:03 am

Re: LRC

Post by samaneh » Tue Jan 19, 2016 10:24 am

Dear Daniele,
Thank you for your attention.
S. Ataei, PhD student at University of Tehran, Iran.

samaneh
Posts: 165
Joined: Tue Jan 21, 2014 9:03 am

Re: LRC

Post by samaneh » Wed Jan 20, 2016 8:43 am

Dear Daniele,
Would you please tell me if you could solve the problem?
Sorry I am in a bit horry and I need to know the problem!
Thank you
S. Ataei, PhD student at University of Tehran, Iran.

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Daniele Varsano
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Re: LRC

Post by Daniele Varsano » Wed Jan 20, 2016 11:54 am

Dear Samaneh,
in your input it is missing the tddft keyword.
More precisely:
#
# GPL Version 3.4.1 Revision 3187
# http://www.yambo-code.org
#
optics # [R OPT] Optics
chi # [R CHI] Dyson equation for Chi.
tddft
StdoHash= 20 # [IO] Live-timing Hashes
Nelectro= 187.0000 # Electrons number
ElecTemp= 0.001 eV # Electronic Temperature
.....

Why this happens I do not understand. Anyway, it seems you are using a quite old version of Yambo.
I strongly suggest to update to the last release (3.4.2 revision 93), as in the meantime many bug have been fixed.
If you downloaded the code by svn you can update the code simply typing:

Code: Select all

svn update
in the yambo directory. Otherwise follow the instruction in the download page of the yambo website.

It is also possible that in your old release the tddft keyword would have to be activated by command line (-t if I'm not wrong), type yambo -H in order to see id this is the case.

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/

samaneh
Posts: 165
Joined: Tue Jan 21, 2014 9:03 am

Re: LRC

Post by samaneh » Sat Jan 23, 2016 7:09 am

Dear Daniele,
Thank you for your reply.
But I tried -t and -H options there was no option for tddft
can you help me more
since I have to continue my jobs with yambo 3.4.1 rev 61 ?!
Best regards
S. Ataei, PhD student at University of Tehran, Iran.

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Daniele Varsano
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Re: LRC

Post by Daniele Varsano » Sat Jan 23, 2016 1:53 pm

Dear Samaneh,
can you help me more
I would like to, but it is not easy as I cannot reproduce your error.
I have to continue my jobs with yambo 3.4.1 rev 61 ?!
Why? The old database should be totally compatible with the new release so you should not loose the results of the old calculations.
Anyway, try to edit your input file by hand adding the tddft keyword:

Code: Select all

optics # [R OPT] Optics
chi # [R CHI] Dyson equation for Chi.
tddft
...
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/

samaneh
Posts: 165
Joined: Tue Jan 21, 2014 9:03 am

Re: LRC

Post by samaneh » Sun Jan 24, 2016 1:31 pm

Dear Daniele,
Thank you for your help.
Do we need all the Transferred momenta
to do tddft or just one is enough (like rpa calculations)?
"QpntsRXs
1 | 39 | # [Xs] Transferred momenta"
Best
S. Ataei, PhD student at University of Tehran, Iran.

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Daniele Varsano
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Re: LRC

Post by Daniele Varsano » Sun Jan 24, 2016 1:36 pm

Dear Samaneh,
you are looking at the optical response, so you need to look at the q=0 limit, which is achieved by
"QpntsRXs
1 | 1 | # [Xs] Transferred momenta
"

If you are also interested at finite momenta electron energy loss spectra (EELS), you select the momenta you are interested in.
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/

haseebphysics1
Posts: 145
Joined: Sat Aug 17, 2019 2:48 pm

Re: LRC

Post by haseebphysics1 » Sat Feb 22, 2020 6:25 pm

Dear developers, sorry for asking a question on the weekend! I was going to run a calculation that's why I could not wait!

I've done static LRC TDDFT and now looking for dynamic LRC and found a following suggested paper:

PHYSICAL REVIEW B72, 125203, 2005 (Silvana Botti et al.)

In the above-mentioned paper alpha and beta, parameters are fitted to BSE or experimental data and equations for alpha and beta are given which are related to physical constants of the materials (as you can see in the attached pic). Now, my question is to find alpha I need to know, resonance frequency (or average absorption gap) since I have the experimental curve for my material, I can read it from there! Max absorption point of energy... Right?

but I also need plasma frequency (w_p) to estimate the alpha for the xc-kernel. In Quantum ESPRESSO epsilon.x code, plasma frequency also gets printed in the output file, but how can I get it from Yambo output?

Thanking you,
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Haseeb Ahmad
MS - Physics,
LUMS - Pakistan

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