Yambo Community Forum

Dear All,

In the tutorial 2, BSE calculation of Hydrogen chain, only the KfnQP_E parameter is changed to open the gap, and the XfnQP_E left unchanged, what's the difference between these two parameters? they are all used to gap Opening? Thanks.

X.Zhu
Nanyang University,
Singapore.

xixi wrote: In the tutorial 2, BSE calculation of Hydrogen chain, only the KfnQP_E parameter is changed to open the gap, and the XfnQP_E left unchanged, what's the difference between these two parameters? they are all used to gap Opening?

With KfnQP you correct the levels that define the basis to solve the Bethe-Salpeter equation (the electron-hole pairs). With XfnQP_E, instead, you correct the levels of the screened interaction. This is to perform a BS calculation on top of GW corrected levels but using a LDA screened interaction.

Hi Andrea,
Thanks for the explanation.
May I know whether there will be a converged result by using either of these two parameters repectively?
Thanks !

andrea marini wrote:

xixi wrote: In the tutorial 2, BSE calculation of Hydrogen chain, only the KfnQP_E parameter is changed to open the gap, and the XfnQP_E left unchanged, what's the difference between these two parameters? they are all used to gap Opening?

With KfnQP you correct the levels that define the basis to solve the Bethe-Salpeter equation (the electron-hole pairs). With XfnQP_E, instead, you correct the levels of the screened interaction. This is to perform a BS calculation on top of GW corrected levels but using a LDA screened interaction.

xixi wrote: May I know whether there will be a converged result by using either of these two parameters repectively?

Sorry but I do not get the question. The QP corrections must be calculated or extracted by some published results. What do you mean as a converged result ?