where can I find "Local Field" ?

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where can I find "Local Field" ?

Postby arlonne » Wed May 29, 2013 4:52 pm

Dear developers,

the definition of Local field confused me very much. In a textbook, it is the dipoles induced electric field that an atom felt. but in Francesco Sottile's PHD thesis, it is relate to Coulomb potential in the response function: X=(1-X^(v0+vLF))-1X^, where vLF corresponding to LF. I think this definition may close to "LF" we are using in optical properties. Therefore, in yambo code, which subroutines calculate the local field?

Thanks advance,
arlonne
arlonne
Department of Physics and Astronomy
Northwestern University, IL 60208
arlonne
 
Posts: 26
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Re: where can I find "Local Field" ?

Postby Daniele Varsano » Wed May 29, 2013 7:21 pm

DearArlonne,
the definition you find in the PhD thesis is what is meant for Local field effects in optical spectra.
The calculation is done in
src/pol_function/X_s.F
LF is equivalent to solve the TDDFT equation in linear response:
\chi=\chi^0+\chi^0(v+fxc)\chi
with an Fxc=0
and it is defined here:
Code: Select all
118 do i1=1,X%ng ! no Fxc [delta_(g1,g2)-Xo(g1,g2)*v(g2)]
119      tddftk(:,i1)=tddftk(:,i1)-Xo(:,i1)*4.*pi/bare_qpg(iq,i1)**2
120      tddftk(i1,i1)=tddftk(i1,i1)+1.
121    enddo

resulting in:
\chi=(1-v\chi^0)^-1\chi^0
that is what you find in the PhD thesis.

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: where can I find "Local Field" ?

Postby arlonne » Wed May 29, 2013 8:30 pm

Dear Daniele,

Thank you very much.

Best,
arlonne
arlonne
Department of Physics and Astronomy
Northwestern University, IL 60208
arlonne
 
Posts: 26
Joined: Thu Apr 18, 2013 4:50 pm


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