where can I find "Local Field" ?

[arlonne]

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

[Daniele Varsano]

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

[arlonne]

Dear Daniele,

Thank you very much.

Best,
arlonne