Yambo Community Forum

Posted: **Tue Jun 13, 2023 2:47 pm**

Hi,

I have some questions concerning the QP_table printed in the ndb.QP file.

In a GW calculation I used

%QPkrange                        # [GW] QP generalized Kpoint/Band indices
1|3|25|28|
%

which returns the QP_table

Code: Select all

QP_table =
  25, 26, 27, 28, 25, 26, 27, 28, 25, 26, 27, 28,
  25, 26, 27, 28, 25, 26, 27, 28, 25, 26, 27, 28,
  1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3 ;

What does the second row stand for? Is one of the first two rows the read-in KS band indeces and the second one the GW-corrected band indeces?

A second maybe more theoretical question: Can the GW correction - as implemented in YAMBO - potentially change the band-ordering?

Best,
Franz

Posted: **Tue Jun 13, 2023 3:13 pm**

Dear Franz,

the QP_table, in principle, can also contain non diagonal matrix elements <n|\Sigma|n'>, this is needed for instance in self-consistent calculation.
In your example, it seems a standard GW calculation, only the diagonal elements are computed so the second line (n') is the same of the first line (n).

About your second question, you can have band switches, but the index is not updated.

Best,
Daniele

Posted: **Tue Jun 13, 2023 7:33 pm**

Dear Daniele,

thanks for the fast answer.

Best,
Franz

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