QP_E in BSE

[sdwang]

Dear developers:
I calculate BSE with ./yambo -b -o b -y h -V 2. for
% KfnQP_E
0.000000 | 1.000000 | 1.000000 | # [EXTQP BSK BSS] E parameters (c/v)
and
% XfnQP_E
0.000000 | 1.000000 | 1.000000 | # [EXTQP Xd] E parameters (c/v)
They are two QP corrections for -o b and -b ,respectively.(Am I right?)
My question is: If I input the QP correction, Should I insert the QP correction value in KfnQP_E and XfnQP_E ,or only one QP correction needed, if this case, which is necessary?

S D Wang

[myrta gruning]

Hallo,

They are two QP corrections for -o b and -b ,respectively.(Am I right?)

Yes you are right. This corresponds to two "places" where you can introduce the QP correction.

1. In the construction of the BS Kernel (here you correct the energy differences that appear in the diagonal of the BS Hamiltonian)
2. In the construction of the Chi, thus in the screening

My question is: If I input the QP correction, Should I insert the QP correction value in KfnQP_E and XfnQP_E ,or only one QP correction needed, if this case, which is necessary?

This depends on you. What is usually done is to correct only the BS Kernel, so inserting the correction and band streching in the % KfnQP_E. In fact if you put a simple scissor this will simply rigid shift your spectrum.
Inserting QP correction in the screening is usually more delicate, since you will modify the screening from KS quantities (orbital energies and wfns), that is usually good.

Hope this helps,
Myrta

[sdwang]

Thank you very much!