Yambo Community Forum

Dear Developers,

I am using YAMBO to calculate the quasi-particle band structure of the mos2/wse2 heterojunction. But the calculated GW band structure is non-ideal due to some bands get tangled up. How can I solve this problem? Thank you!

Best regards,
Ying Chen

Dear Ying Chen,
check first if this is a failure of the band interpolation, or if effectively this is consistent with the points you calculated the GW correction.
It may happen that you just need to calculate more occupied bands to recover a correct behaviour.
Next, you can try to interpolate corrections instead of QP energies.
In order to do so, you need first to calculate your DFT band structure with QE, and next indicate theat PW_SAVE directory in your input file,
something like: The PW_SAVE directory will contain a SAVE directory generated by p2y.

Best,
Daniele

You can also try to change
the interpolation method

INTERP_mode= "BOLTZ"

and see if it helps

best
Claudio

Dear Dr. Daniele,

Thank you very much for your suggestions. I have checked the process of band interpolation and found an error of "<02s> [INTERPOLATION@E_on_built_in] Errors: Max, Avg, Avg_rel = 1.34691596E-04 9.39816618E-06 1.26988976E-04". The relevant reports are as follows:

<01s> [06] Interpolation tool
<01s> [06.01] Loading special Points for the Unknown lattice
<01s> [WARNING]Unknown lattice unit cell
<01s> [06.02] External/Internal QP corrections
<01s> E<./all_Bz/ndb.QP[ E-E PPA E-E PPA: 27.21138 XG: 235 Xb: 1 80 Scb: 1 100]
<01s> [dE_from_DB-Nearest K] Exact matches [o/o]: 100.0000
<01s> [06.03] Interpolation@work: Circuit
<01s> Number of K-points in the circuit : 72
<01s> [INTERPOLATION] Number of shells: 4432
<02s> [INTERPOLATION@E_on_built_in] Errors: Max, Avg, Avg_rel = 1.34691596E-04 9.39816618E-06 1.26988976E-04
<02s> [06.04] Interpolation@work: Spin and Magnetization
<10s> Spinor Components |########################################| [100%] 07s(E) 07s(X)
<10s> [spin-Nearest K] Exact matches [o/o]: 1.357466
<10s> [spin-Nearest K] Neighbours [user]: 1
<10s> [spin-Nearest K] [real]: 1
<10s> [spin-Nearest K] Interpolations [o/o]: 98.64253
<19s> Magn-factor |########################################| [100%] 09s(E) 09s(X)
<19s> [magnetization-Nearest K] Exact matches [o/o]: 1.357466
<19s> [magnetization-Nearest K] Neighbours [user]: 1
<19s> [magnetization-Nearest K] [real]: 1
<19s> [magnetization-Nearest K] Interpolations [o/o]: 98.64253
<19s> [06.05] Fermi Levels
<19s> Fermi Level (BUILT-in bands) [eV]: 0.3140905
<19s> [06.06] Bands output
<19s> [07] Game Over & Game summary

What does that mean? How can I avoid this error?

Best,
Ying Chen

Dear Ying Chen,
this is not an error of the calculation, but it indicates the error in the interpolation procedure which is actually small.
I suggest you check carefully if your QP corrections are compatible with the interpolation, if not please see the Caludio's suggestion in changing the inteprolation method. Finally, you can try the method I proposed to you in my first reply.
Best,
Daniele

Dear Daniele and Claudio,

I have tried to change the interpolation method to "BOLTZ" ,
calculated more occupied bands in the "gw_ppa_all_Bz.in" , and calculated DFT band structure with QE and indicate the "PW_SAVE" which is generated by p2y after calculating the QE band in my input file. But the result of interpolation does not seem to improve.

Best,
Ying Chen

Dear Ying Chen,
can you post the report file of your GW calculation together with the output of the interpolation?
Best,
Daniele

Dear Daniele,

I have show the output and report files in the attachments. Thank you very much for your help!

Best,
Ying Chen

Dear Ying Chen,
sorry, but the output you sent does not look like the plot you have shown before.
Please, see plot attached.
[attachment=0]

Best,
Daniele

Dear Daniele,

I am sorry for I just summited the output of another material Ga2O3 because I have tried your method on this material. The eight bands you shown is normal, but the bands with higher energy cross each other,

So is it a normal phenomenon?

For the plot I have shown before, the output and report files is shown in the attachments.

Best,
Ying Chen