EPW Forum

Dear all, I calculate matrix g (EPW5.2) for monolayer H-NbSe2, however, I find a problem that |g(k,k+q)| is inconsistent with |g(k+q,k)| for some k/q points. An example is shown below: 1.png 2.png In this case k=(-0.3333334,0.3333334,0), k+q=(-0.3333334,0.6666667,0). The energies of enk and enk+q ar...

Dear H. Lee, Thank you! The tag eps_acustic works for phonon linewidth. After considering the factor of 2: the linewidths between qe and epw are very similar except for small difference: epw&qe linewidth.png I also calculated electron-phonon coupling matrix g (lowest phonon - the band which cros...

Dear H. Lee, Thank you for your patient explanation. I note that another thing different from epw and qe: The prints from EPW/src/ephwann_shuffle.f90 doesn't mention the square of the electron-phonon matrix, and in EPW/src/selfen.f90: ! SP: The expression below is the imag part of phonon self-energy...

Dear Professor S. Ponce, Thank you for your comments. I tried to increase the nkf, nqf, fsthick and observed the same lead linewidth as before. Yes, it is a factor 2 difference between qe and epw result. As the imaginary part of phonon self-energy is the half of phonon linewidth, we should expect th...

Dear H. Lee,

Thanks for reminding, I ignored this point.
I recalculated the epw using the correct degaussw=0.68eV (0.05*13.6), the epw results became more close to the qe results. Maybe I should increase nkf/nqf in epw to obtain better results.

Sincerely,
Zishen

Dear H. Lee, Thank you very much for your reply. Yes, the q-path is QE and EPW are given in a different way, but we noted that the high symmetry paths are same. And the tutorial indeed said the results are under converged. I recalculated the example using high accuracy: For qe: scf0.in 32*32*32 scf....

As you may note, the Pb phonon linewidth given by ICTP tutorials from qe and epw are also different except for their different units. (EPW only shows linewidth of third phonon which corresponds to the highest branch in the QE linewidth). I am still confused about the problem...

Dear all, Recently, I try to use EPW to study CDW property. The bandstructure and phonon dispersion are perfect agree with the QE results. But their linewidth of the lowest phonon has large differences. phonon linewidth.png Is this a normal phenomenon because EPW has more dense k/q points than QE? I...