EPW Forum

Hi,

You need to converge lambda with both k and q meshes. This is not very easily done in QE since the k and q meshes used are in general pretty coarse.

Best,
Roxana

Hi, The *** means that not enough digits are printed. Currently, the format in selfen.f90 if f15.6. You can change this to more digits. However, the values that you are getting appear too large. selfen.f90: 104 FORMAT(5x, 'lambda_tr( ',i3,' )=', f15.6, ' gamma_tr=', f15.6, ' meV', ' omega=', f12.4 ...

Hi,

Can you please also use the latest released version 5.7?

Best,
Roxana

Hi,

Please post questions about QE on the QE forum.

Best,
Roxana

Hi,

Larger the \mu* value stronger the Coulomb effect and therefore smaller the Tc and gap.

Best,
Roxana

Hi,

You can find a tutorial with input file under the "Hands-on tutorial: Polarons" at the link below:

https://epw2023.dryfta.com/74-schedule

Best,
Roxana

Hi Shubham,

I would recommend running calculations with different \mu* values starting from \mu*=0 and see at which value the lower gap becomes negative.

Best,
Roxana

Hi Rachel,

There is no flag to do this in the code. You can modify the subroutine where |g| is written to file.

Best,
Roxana

Hi,

I just noticed that the e-ph coupling strength in your output file is zero. It appears that something went wrong when reading a2f file. So check that the is correct.

"Electron-phonon coupling strength = 0.0000000"

Best,
Roxana

Hi,

You can vary mu* between 0.1 and 0.2 and see how Tc changes (most systems have mu* between these limits). As an alternative, you can estimate mu* for your system using Morel-Anderson expression.

Best regards,
Roxana