Yambo Community Forum

Hi,

I have a question regarding the inclusion of retardation effects in optical properties calculations at the RPA level.

As I understand, the standard RPA formalism implemented in Yambo includes only the longitudinal component of the electromagnetic field (the Coulomb field) while neglecting the retardation effect of the transverse field. Is this understanding correct?

If so, is there any way to include retardation effects in the calculation of optical properties using Yambo?

Additionally, would TDDFT offer a way to incorporate such effects within Yambo, or is this outside the scope of the software?
Would you please suggest how one can include the effect?

Thank you for your time.


Best Regards
Ehsanul Azim
Masters student, Mechanical Engineering
University of Texas Rio Grande Valley (UTRGV)

Dear Ehsanul Azim,
your question goes back to the definition of the MB hamiltonian from which both DFT/TDDFT and MBPT are derived.

The MB hamiltonian underlying these theories contains only the instantaneous and longitudinal electron-electron interaction. This is the theory used in the yambo code.

Derivations which include also the retarded transverse interaction, e.g. the (expectation value of) the photon propagator are available in the literature.
This can be included only for the macroscopic classical part (easier), or also into the microscopic/quantistic terms (that's a step towards QED).
See for example these works (there are more, also within TDDFT):
https://journals.aps.org/prb/abstract/1 ... .93.155102
https://journals.aps.org/prb/abstract/1 ... vB.29.4631

Best,
D.

Dear Davide Sangalli,

Is there any software you know of that can handle the issues (Transverse electric field)?

Thank you so much.

Best Regards
Ehsanul Azim
Masters student, Mechanical Engineering
University of Texas Rio Grande Valley (UTRGV)

Dear Ehsanul,

I'm not an expert on the topic, but you can have a look to the Octopus code. This is a tddft code, and I think that some work has been done in that direction.
You can have a look if you find in the manual features that fits your needs, or alternatively have a look at the literature and ask to the authors.

Best,

Daniele