Yambo Community Forum

Dear Yambo team,

Can yambo deal with systems with odd number of electrons? Or a more general question, can the DFT+GW+BSE procedure deal with odd number of electrons?

I know some sort of quamtum chemistry techniques. For odd-number of electrons, unrestricted Hartree-Fock method is essential. But I know little of the philosophy how DFT and GW/BSE deal with it.

Do I need spin-polarized calculations? Are there any special treatment?

Best,
Yubhai

Dear Yunhai,
yes you need a spin-polarized calculation. The ground state can be calculated using quantum-espresso or abinit. Next, Yambo can do GW/BSE on top of it.
Best,
Daniele

Daniele Varsano wrote:Dear Yunhai,
yes you need a spin-polarized calculation. The ground state can be calculated using quantum-espresso or abinit. Next, Yambo can do GW/BSE on top of it.
Best,
Daniele

Daniele,

Thank you for the reply.

Since for odd-number of electrons the picture of singlet and tripet breaks down, how to deal with the BSE kernel? Does it contains both the exchange term and direct term?

Best,
Yunhai

Dear Yunhai,
In this case, the BSE is solved directly in the spin space:
You can have a look to this post:

viewtopic.php?f=28&t=789&start=20#p3389

Best,

Daniele

Daniele Varsano wrote:Dear Yunhai,
In this case, the BSE is solved directly in the spin space:
You can have a look to this post:

viewtopic.php?f=28&t=789&start=20#p3389

Best,

Daniele

Ok, I will consult that post.

Best,
Yunhai