Total energy

[zchen]

Hi everyone:
We know yambo is good to calculate the GW approximation and the excitation spectra. When I finish GW calculation I can find the band gap but I cannot find the TOTAL ENERGY of the molecule. My calculation is very interested in the total energy under GW approximation.


Zhifan Chen
Departmeent of Physics
Clark Atlanta University
USA

[weic]

The total energy is (as far as I know) not implemented with the current GW scheme in YAMBO.

[zchen]

Is there any way we can calculate the total energy form yambo GW output? or other yambo calculation.

[zchen]

If we would like to compare the energy difference between two molecules can we use GW output to estimate the self-energy + total energy we calculated from DFT for these two molecules?

[Daniele Varsano]

Dear Zhifan Chen,
first of all let me ask you to fill your signature in your profile as it will be automatically
reported in each of your post.

The total energy expression from a one-particle Green function formalism can be obtained
thanks to the Galitski-Migdal expression. You can look for instance to some review or lectures
that can be downloaded in the yambo website in the lecture section.
See for instance the Varsano and Gatti lecture!!.
Unfortunately the Galitski-Migdal expression for the total energy it is not implemented in Yambo, and
to my knowledge, I did not see these calculations in GW approximation for real materials, but just for
jellium,jellium slabs or other models, see for instances some articles by R. Godby
(but here may be I'm wrong and someone can correct me). In Yambo there is the possibility to calculate
the total energy in the RPA approximation, using the adiabatic connection, as done in the paper
First-Principles Description of Correlation Effects in Layered Materials
by A. Marini, P. Garcia-Gonzalez, and A. Rubio Phys. Rev. Lett., 96, 136404 (2006), but this part it is not in the
GPL version, and sincerely I don't' know if it will be released soon in the GPL version.
Best,

Daniele