Yambo Community Forum

Dear Developers,
I have a question about the "diagnol only" option. What's the meaning about this? I couldn't find more information about this
option except in excitonic Hamiltonian's resonant part we have diagnol, exchange and screened coulomb parts. (the yambo documentation: http://www.yambo-code.org/doc/docs/doc_BSS.php )
But I believe the "diagnol only" has nothing to do with the diagnol part here. So what does this mean?

Another question is about the explanation about "BSresKmod"
http://www.yambo-code.org/doc/vars/var_BSresKmod.php
The [c] means "coupling part"? I am a little confused, because from the explanation about BSE kernel, I would accept it is
the Coulomb term in resonant or coupling part, since we also have this option in "BScplKmod" (Coupling Kernel mode)
thank you!
yuan ping
university of california, Davis

Hallo Yuan Ping,

For sake of clarity I splitted off your post from the topic you had replied to and gave to it a different subject. This is important in case someone with similar questions/problems will search the forum. (so in general it is a good practice to create a new topic for any new question/problem trying to give a specific/precise subject. Thanks!)

yping wrote: Another question is about the explanation about "BSresKmod"
http://www.yambo-code.org/doc/vars/var_BSresKmod.php
The [c] means "coupling part"? I am a little confused, because from the explanation about BSE kernel, I would accept it is
the Coulomb term in resonant or coupling part, since we also have this option in "BScplKmod" (Coupling Kernel mode)

You are right this is quite confusing, and not consistent with the related doc, thank you for pointing it out.
Yes, [c] refers to the Coul part in the doc_BSS.

About the [d], the notation in the doc_BSS is a bit misleading. There "diag" is used there to indicate just the one-particle energy differences, whereas I think that in the BSresKmod [d] refers to the diagonal contributions (v=v', c=c', k=k') of the exch and Coul parts (in the doc_BSS notation).

cheers,
m