Search found 616 matches

by sponce
Fri Jul 31, 2020 3:08 pm
Forum: General discussion
Topic: EPW phonon linewidth inconsistent with QE results
Replies: 11
Views: 7350

Re: EPW phonon linewidth inconsistent with QE results

Dear Zishen, Indeed you can try increasing the fine grids (especially the q one) in EPW. This being said, it seems like the curves are the same/very similar but there is just a factor 2 difference. You can take a look in EPW/src/selfen.f90 and look for the selfen_phon_q subroutine where the equation...
by sponce
Mon Jun 15, 2020 3:38 pm
Forum: General discussion
Topic: Boltzmann transport equation
Replies: 1
Views: 1937

Re: Boltzmann transport equation

Hello, In the case of metal, you should use the input variable assume_metal = .true. In that case the variable ncarrier is not used since the number of carrier is determined based on the Fermi-Dirac distribution at the Fermi level. In the code you can track the variable assume_metal to understand be...
by sponce
Mon Jun 15, 2020 10:10 am
Forum: Running the code
Topic: Questions about phonon self-energy of different temperatures
Replies: 1
Views: 1974

Re: Questions about phonon self-energy of different temperatures

Dear Yd Huang,

I have never tried it but it sounds like a good idea.

Let us know if you are able to make this work. Would be very interesting !

Best,
Samuel
by sponce
Mon Jun 15, 2020 10:08 am
Forum: Running the code
Topic: How to make EPW print XXX.sigma_restart1 files?
Replies: 1
Views: 2026

Re: How to make EPW print XXX.sigma_restart1 files?

Dear Mikhail, It depend on the version of the code you are using. Note that the restart_freq has been renamed into restart_step now. On the most recent version of the code, I think the XX.sigma_restart are not used anymore. Instead it uses the restart_ibte.fmt file (will be renamed soon into restart...
by sponce
Mon Jun 15, 2020 10:04 am
Forum: Running the code
Topic: Setting a high carrier concentration for GaN transport problem
Replies: 1
Views: 2090

Re: Setting a high carrier concentration for GaN transport problem

Dear Sai, First let me state that the tuto, as indicated, is totally unconverged and is intended to be fast. In particular the DFT bandgap of GaN is strongly underestimating the experimental one. The default EPW implementation is to do intrinsic carrier mobility. The initial Fermi level (fermi_energ...
by sponce
Mon Jun 08, 2020 4:00 pm
Forum: General discussion
Topic: what are Z and lam printed in epw output
Replies: 1
Views: 2493

Re: what are Z and lam printed in epw output

Dear Gautam, The Z is the correction factor obtained via linearization to account for the fact that the electron self-energy should be evaluated at the renormalized eigenvalues but they are evaluated at the bare KS eigenvalue. E_nk = e_nk + Re Sigma(E_nk) E_nk \approx e_nk + Z_nk Re Sigma(e_nk) Best...
by sponce
Mon Jun 08, 2020 3:49 pm
Forum: General discussion
Topic: Resistivity of Pb using BTE
Replies: 1
Views: 1917

Re: Resistivity of Pb using BTE

Dear Vahid, For metal, one typically look at the conductivity or resistivity but not mobility. Indeed you can compute the conductivity using the BTE instead of the Ziman formula in EPW. In the development version on GitLab, look for the new input variable 'assume_metal' to do that. Best wishes, Samu...
by sponce
Mon Jun 08, 2020 9:05 am
Forum: Running the code
Topic: Screening of electron-phonon matrix by free carrier
Replies: 4
Views: 4224

Re: Screening of electron-phonon matrix by free carrier

Dear Sai, First, let me clarify the mobility implementation. The default implementation assumes the intrinsic regime (relatively low carrier) and the mobility is independent of the carrier concentration. The way the Fermi level is computed is by having the Fermi level inside the bandgap and adjustin...
by sponce
Fri Jan 24, 2020 9:13 am
Forum: Electron-phonon
Topic: electron-phonon coupling at Gamma point
Replies: 1
Views: 19208

Re: electron-phonon coupling at Gamma point

Dear Claudio, Sorry for the very late reply. Exactly at \Gamma, its not decided. The code returns the value of \omega and g without the non-analytical part (exactly what you get from a direct DFPT calculation at \Gamma). For info, the tolerance on "exactly \Gamma" is 1E-8 in crystal unit. ...
by sponce
Fri Jan 24, 2020 8:55 am
Forum: General discussion
Topic: Run Wannier90 and EPW separately.
Replies: 5
Views: 4334

Re: Run Wannier90 and EPW separately.

Dear Cathy,

This is probably not so simple to do.
Why not simply running EPW which will call Wannier90 internally.

EPW supports most of w90 features.

You can always add w90 input variables inside the EPW input file by adding them through the "wdata(X)" keyword.

Best,
Samuel