No Absorption with BSE calculation on monolayer MoS2

[Daniele Varsano]

Dear Reza,

it seems there is a problem in the calculation done in IRENE machine.
In both calculation, you can directly compare the value obtained in the report file for the exchange correlation potential to the one printed in the output of Quantum Epsresso. They should be the same (unless you are using pseudopotential with non-linear core correction, and in this case you need to activate it in the yambo input "UseNLCC" flag)
IRENE:

Code: Select all

[xc] E_xc :  -1.669805 [Ha]
      E_xc :  -3.339610 [Ry] 

MESU:

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[xc] E_xc :  -56.95219 [Ha]
      E_xc :  -113.9044 [Ry]

My guess is that MESU provides you the consistent results.

Then, if it so, to understand what is going wrong in IRENE as a first test I would check if there is some problem with MPI parallelism (check consistency using a different number of MPI tasks) or with linear algebra: if you used system lin-algebra libraries you can try to use internal one by adding in the configure command line:
./configure --enable-int-linalg ....

Best,
Daniele