kernel approximation

[samaneh]

Hi there,
would you please explain the difference between these commands:
yambo -d -k hartree -g n -p p and yambo -g n -p p

also would you please explain difference among these approximation kernels:
Time-dependent Hartree yambo -k hartree
Time-dependent DFT: ALDA yambo -k alda
Time-dependent DFT: long-range yambo -k lrc
Time-dependent Hartree-Fock yambo -k hf
Full BSE with screened interaction yambo -k sex
Static screened interaction yambo -b

thanks
S. Ataei, PhD student of Condensed matter physics, university of Tehran, Iran

[Daniele Varsano]

Dear Samaneh,

yambo -g n -p p
this is the command line for a GW calculation in plasmons pole approximation.
while yambo -d -k hartree -g n -p p does not make nay sense to me.

About the other runlevels you wrote, they are indicated. If you do not what they mean, I strongly suggest you to study the background of first principle excited states calculations before doing any calculations. In the yambo website you can find a lot of useful documentations:
http://www.yambo-code.org/theory/lectures.php

also the PhD thesis can be useful to start:
http://www.yambo-code.org/publications/theses.php

Best,
Daniele

[samaneh]

Dear Daniele,

Thanks a lot, yes I know but I saw this strange command "yambo -d -k hartree -g n -p p"
in tutorial "Basic concepts of the GW approximation for bulk Silicon"!!!
Best regards
S. Ataei

[Daniele Varsano]

Dear Samaneh,
ok I see.
The string yambo -d -k hartree -g n -p p it explicitly indicates that the PP approximations is used and dielectric matrix for the two frequencies of the PP model are calculated in the RPA approximations (ie Hartree kernel).
When typing yambo -p p -g n, it is the same think as the RPA for the dielectric matrix it is the default.
Best,
Daniele

[samaneh]

Dear Daniele,
Thanks.
you mean yambo -d -k hartree -g n -p p is the same as yambo -g n -p p.
But Can I use full BSE kernel to perform GW calculations?
using "yambo -d -k sex -g n -p p"
Best regards
S. Ataei

[Daniele Varsano]

No as it does not make any sense.
Gw is an approximation for the self energy while the bse is an equation for the polarization.
Best
Daniele

[samaneh]

Dear Daniele,
Many thanks.
Best regards
S. Ataei