Drude term

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.

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Drude term

Postby neets » Tue Sep 04, 2018 12:18 pm

Hello,

I’m confused about how to get the data of DrudeWXd in a specific metallic system. Shoud I calculate the Drude frequency from the Eq(2.17) in the Andrea' thesis.

Best,
neets
Sincerely
neets
Ph.D student
Department of chemical physics,
USTC[/quote]
neets
 
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Re: Drude term

Postby Daniele Varsano » Thu Sep 06, 2018 4:05 pm

Dear Neets,
please sign your post with your full name and affiliation, this is a rule of the forum, you can do once for all by filling the signature in your profile.
In order to take into account the Drude tail, Yambo uses the Drude model, so the DrudeWXd frequency enters in the input as an empirical parameter.
Usually, the value of the Drude frequency and width is taken from the literature, in general from experiments or previous calculations.
The expression you found in Andrea's thesis is not implemented in Yambo anymore as very heavy and impractical.

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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Re: Drude term

Postby neets » Fri Sep 07, 2018 6:23 am

Dear Daniele,

Thank you for your reply. As you said, the Drude frequency and width is taken from experiments or previous calculations generally. What should we do when we are interested in the Plasmon Resonance of a new metallic system ?
Sincerely
neets
Ph.D student
Department of chemical physics,
USTC[/quote]
neets
 
Posts: 2
Joined: Mon Sep 03, 2018 2:23 pm

Re: Drude term

Postby Daniele Varsano » Tue Sep 11, 2018 5:39 pm

Dear Neets,
it depends on what you are interested in,

if you are interested in plasmons I suggest you:
1) to look at the eels spectrum, you can see it at RPA level and if you
are interested in a particular q vector and it converges with respect the k point sampling then intraband transitions
are included and you should not need the Drude term.
2) If you are interested instead to the q=0 response you can see at what frequency the plasmon is located. If it is far from w=0 then the Drude term even if
there should not affect that much the position of the plasmon.
3) If this is not the case, a possibility could be to look at finite q increasing k point sampling for smaller and smaller q point toward zero, fit the Drude parameters and
extrapolate to q=0. Not sure about the precision of this workaround.

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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Daniele Varsano
 
Posts: 1950
Joined: Tue Mar 17, 2009 2:23 pm


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