Yambo Community Forum

Dear all!

I am trying to compute the induced density in a metal slab, which I ultimately want in the direction perpendicular to the slab, i.e. integrated over the two periodic directions. To this end, I compute the RPA response function and get the real- and imaginary part of alpha. Now, the induced density (in linear order) should be the integral over the ground state density and the density-density response function. Is there a possibility how I can get the latter in real-space from Yambo?

Many thanks,
Christian

Dear Christian,
yambo can give you the response function in G-space. X_{G,G'}(q,\omega)
Page 7 here: https://wiki.yambo-code.eu/wiki/index.p ... heatsheets --> https://wiki.yambo-code.eu/wiki/index.p ... 5.0_P7.png

What you probably (?) want is the induced density
rho_G(q,\omega) = sum_G' X_{G,G'}(q,\omega) V^{ext}_{G'}(q,\omega)

If you are fine with the q=0 and \omega=0 the info you need is printed in the database of the screening ndb.em1s_fragment_1.
Probably with yambopy you can try to code the above equation by reading the ndb.em1s_fragment_1 or similar.

Best,
D.

Dear Davide!

Many thanks for your reply!

1) What runlevel would I need such that ndb.em1s* are stored? With "yambo -o c -k Hartree -r" only the dipoles and RIM/cutoff are stored.

2) Can I also access the X_{G,G'}(q,\omega) elements for \omega > 0? If I understand correctly, those are controlled by "ETStpsXd" and "EnRngeXd"?

Cheers,
Christian

For the static screening: https://wiki.yambo-code.eu/wiki/index.p ... _screening

If you want the frequency dependent screening use either multi-plasmon pole (MPA) or full freqeuncy (FF) https://wiki.yambo-code.eu/wiki/index.p ... tion_(MPA)

Pleas notice that, however it is not directly the reponse function which is written in the databases, but v(G)*X_{G,G'} (if I'm not wrong), both in the static and in the dynamical case

There is in principle also the option which directly prints the response function, but it is not very much tested.

Best,
D.

Dear Christian,

just a small warning. In metals, in the long range limit q->0 intraband contribution to the response functions are not taken into account, while they are for finite q. What you can do is to extrapolate the q->0 limit from the calculated values at finite q.

Best,
Daniele