EPW Forum

Hi Ilias,

Sorry for the late reply. You can work with the mode-resolved Eliashberg spectral function for this analysis. Also, the cumulatively integrated lambda is written to the prefix.a2f file, which you can use for further analysis.

Best,
Shashi

Hi Jyoti,

The mode-resolved scattering rate has been implemented in EPW v6.0. You can enable it by setting iverbosity = 3.

Hope this helps.

Best,
Shashi

Dear Shubham, You may want to check the behavior at a finite q-point instead of Gamma, since q = 0 can sometimes be special (e.g., degeneracies or phase/gauge issues) that may affect the apparent Hermiticity. Also, does your system preserve time-reversal symmetry? This can influence the symmetry ...

Hi Krishnedu, The EPW histogram is not the usual energy-resolved DOS. It shows the distribution of superconducting quasiparticle gaps Δₙₖ on the Fermi surface, obtained from the anisotropic Eliashberg equations (sum over scattered bands m). So the spread reflects gap anisotropy across k-points, not s ...

Hi Ashwath, In MgB2, the two superconducting gaps are well separated, whereas in MoTe2, the gaps are not as clearly distinct. This difference largely depends on the Fermi surface of the material. For MgB2, the σ and π bands give rise to two well-separated gaps. In contrast, for MoTe2, the gaps are m ...

Hi Bhawna, The error you are encountering may be related to the efermi_read and assume_metal settings, as Xiao pointed out. However, this issue should not appear in the recent EPW v6.0 version. In the latest version, using efermi_read = .true., assume_metal = .true., and lfast_kmesh = .true. works ...

Hi Helin, Thank you for testing the different versions. I’m surprised that the recent versions of EPW are giving significantly different values of λ—this was not expected. Would you mind sharing your input and output files (SCF, NSCF, phonon, and EPW), along with the pseudopotentials and the spec ...

Hi, Once you perform the ph.x, it is not necessary to rerun phonon again. I suggest that if you want to converge on isotropic Tc, you can start with epwread=.true., epwwrite=.false., wannierize=.false., a2f_iso=.true., eliashberg=.true. Setting a2f_iso=.true. performs the isotropic Eliashberg ...

Hi Nikitha, As Xiao pointed out, if DOS is zero there are no states for scattering. If this is indeed what you intend to do, then you need to shift the Fermi energy in EPW by setting efermi_read=.true. and fermi_energy=xx . Also you have not showed EPW input only pasted QE input. In QE, you can not ...

Hi Nikitha, You can use the ZG module of the EPW (see EPW 2023 paper) to compute anharmonic force constants. Using the anharmonic force constants with the harmonic dvscf you can use it for Eliashberg calculations. For the anharmonic special displacement method, see the 16:15-17:45 tutorial on Friday ...