## where can I find "Local Field" ?

Various technical topics such as parallelism and efficiency, netCDF problems, the Yambo code structure itself, are posted here.

### where can I find "Local Field" ?

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?

arlonne
arlonne
Department of Physics and Astronomy
Northwestern University, IL 60208
arlonne

Posts: 26
Joined: Thu Apr 18, 2013 4:50 pm

### Re: where can I find "Local Field" ?

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)**2120      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/

Daniele Varsano

Posts: 1974
Joined: Tue Mar 17, 2009 2:23 pm

### Re: where can I find "Local Field" ?

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