Narrow gap materials is reported to be metallic system by yambo

[liuyang_phy]

Dear developer,

I am trying to do G0W0 calculation for a narrow gap system(around 30 meV calculated by QE) by Yambo. But, when i initialize the database by typing yambo, i found the message below:

[X] === Gaps and Widths ===
[X] Conduction Band Min : -0.950537 [eV]
[X] Valence Band Max : -0.950537 [eV]
[X] Filled Bands : 15
[X] Metallic Bands : 16 17
[X] Empty Bands : 18 420
If i continue to do the GW calculation, there will be an WARNING message ([WARNING] The system is a metal but Drude term not included) in the repore file. Why yambo report a narrow gap system to be metallic ?
How should i deal with this narrow gap system in yambo? Should i include the Drude term and how to include it?

Thank you so much!

Liu Yang
PhD student
Hua zhong university of science and technology, China

[Daniele Varsano]

Dear Liu,

you can try to remove all the ndb* file in the SAVE directory and repeat the setup setting:

Code: Select all

setup
ElecTemp= 0.0 eV 

and see it this solve the problem.

Best,
Daniele

[liuyang_phy]

Dear Liu,

you can try to remove all the ndb* file in the SAVE directory and repeat the setup setting:

Code: Select all

setup
ElecTemp= 0.0 eV 

and see it this solve the problem.

Best,
Daniele

Thank you very much. It seems works normally when i just follow your instructions. But why the default initialization set the electronic temperature to be 0.025861 eV(300K) ?
Best wishes
Liu Yang

[Daniele Varsano]

Dear Liu,
most probably because you used a smearing in the QE ground state calculation and Yambo and QE use a different smearing function.
Best,
Daniele

[liuyang_phy]

Dear Liu,
most probably because you used a smearing in the QE ground state calculation and Yambo and QE use a different smearing function.
Best,
Daniele

Dear Daniele,
Does it means that i should set "ElecTemp= 0.0 eV" in each of my input file (such as G0W0 or BSE calculation) if i used a smearing in the QE ground calculation? looking forward to hearing from you and thank you very much!
Yours sincerely,
Liu Yang

[Daniele Varsano]

Dear Liu Yang,
yes, you should keep it in your calculations.

Best,
Daniele