EPW Forum

Hi Shubham, Could you double check your phonon dispersion and the density of states both with QE and EPW? You can use https://docs.epw-code.org/doc/Inputs.html#band-plot flag to interpolate your band/phonon. One more thing I noticed is that you have "amass(1) = 92.90638, amass(2) = 78.96000," in you...

Hi Shubham, I did not understand what you mean by "did not match". Phdos and a2f are two different quantities calculated using two different equations, and why should they match? One thing I noticed is that your Wannier spreads are large for some of the projections, is that acceptable? Did you check...

Hi Bikash, It looks like a memory issue. Could you please run test-suite/epw_super? https://gitlab.com/QEF/q-e/-/tree/develop/test-suite/epw_super. To run this, you can issue "make run-custom-test-parallel testdir=epw_super" inside qe/test-suite directory. If it passes through, it will confirm that ...

Hi Shubham,

I case of MgB2, system is anisotropic and has two gaps from \Sigma and \Pi bands, but we can not always say that the anisotropic SC gap shows a multi-gap character, I think.

Happy EPWing,
Hari

Hi Simba2828, If a material has a highly anisotropic superconducting gap, it is anticipated that its AD Tc (critical temperature for the isotropic component of the gap) will be lower than its anisotropic Tc. For instance, MgB2 serves as an example where you can refer to the literature and observe th...

Hi Shubham,

You can go through the first paper of the EPW code; https://www.sciencedirect.com/science/a ... via%3Dihub, where you can see the decay plots in Fig. 2.

Happy EPWing,
Hari

Hi Shubham,

As long as you have all bands inside the Fermi window (ie. from -fsthick to +fsthick) and the Wannier functions are well decayed (please plot and compare your Hamiltonian and el-ph decay) it should not affect the Tc and SC gap.

Happy EPWing,
Hari

Hi Shubham, The negative value of superconducting gap is not physical. However, we do not restrict the calculation based on the -/+ value of the superconducting gap, any numerical value is possible in the calculation. If the negative value is too small, that can the a numerical error. I recommend yo...

Hi Huan Tran, First: It looks like your Pade calculation is not converged. I recommend you to decrease the value of "npade" (the default value is 90, https://docs.epw-code.org/doc/Inputs.html#npade) Second: The memory requirement depends mainly on number of k/q points, number of bands inside the Fer...

Hi Sahil,

I think, it would be fine if your calculation is conversed. I always recommend to check the convergence.

Happy EPWing,
Hari