GW vs GGA band gap

[lamia]

Dear Yambo Developers,

I am running GW calculations and obtaining the band structure. However, when I look at the band structure, I see that the band gap (1 eV) of GW is equal to the band gap (1 eV) of DFT-GGA . How is this possible?

Best,

[Palummo Maurizia]

Dear Taouil

without further detail it is impossible to help you.
Please provide at least the input and report files of your GW and ypp post-processing runs.

Best
Maurizia

[lamia]

Dear Maurizia,
Thank you for your reply.
You'll find the input of GW and ypp post-processing runs.

Best,

[Daniele Varsano]

Dear Taouil,
in order to include GW correction in the band structure, you need to provide the QP database in the input file:
GfnQPdb = " E < ./SAVE/ndb.QP"
if the QP database is in the SAVE directory, otherwise you need to indicate the path where the database is.

Best,
Daniele

[lamia]

Dear Daniele,

Should I add GfnQPdb = " E < ./SAVE/ndb.QP" in yambo.in input file or just in ypp.in or both ? I've tried to add it in ypp.in but I still get same band structure.

best,

Lamia

[Daniele Varsano]

Dear Lamia,
the QP correction in G has to be added in the ypp.in. If the bands are the same it means that the QP corrections are not read correctly. To understand what went wrong can you post the report and output?

Best,
Daniele

[lamia]

Dear Daniele,

You'll find the report and output files in the attachments.

Best,

Lamia

[Daniele Varsano]

Dear Taouil Lamia,
from the report it seems the QP corrections are read correctly.
Can you try to repeat the calculation by commenting the BANDS_path variable, and using
GfnQPdb= "E < ./SAVE/ndb.QP"
instead of:
GfnQPdb= "E < SAVE/ndb.QP"
if the correction is not applied please post also the output file.

Best,

Daniele

[lamia]

Dear Daniele,

I've tried with your last suggestion .

PS: I should get an indirect band gap with 2.43 eV
best,
lamia

[Daniele Varsano]

Dear Taouil Lamia,
I was meaning the bands outputs you calculated with and w/o the GfnQPdb input variable.

Best,

Daniele