Procedure to obtain phonon dispersion curve

[anindya@iiita]

Dear EPW experts,
I would like to know that how can I get the phonon dispersion curve data in epw calculation.I would like to see whether my wannier phonon dispersion data matches with the pw phonon data.Which card I need to add in epw.in file to see the phonon dispersion data.Please let me know.

Thanks and regards,
Anindya Bose
Research Fellow,
IIIT Allahabad

[sponce]

Hello,

You need

band_plot = .true.

Then you need to provide the high symmetry path for the phonon on the fine grid with:
filqf = 'path.dat'

where "path.dat" contains your lists of q-points along the path you want.

Everything else can be false like:

elecselfen = .false.
phonselfen = .false.
a2f = .false.

Note that you can also get the electronic BS by doing
filkf = 'path.dat'

At the end of the calculations, you will get a file "band.eig" and "phband.freq".
They are in a format that allows you to use the q-e/bin/plotbands.x on those files to get them in gnuplot format.

Best,
Samuel

[anindya@iiita]

Dear Sir,
If I want to see the phonon curve after a2f calculation ,then I must make a2f,elecselfen and Phonon self energy as true.In that case,won't I be able to find out phonon structure during a2f calculation?

Thanks and regards,
Anindya Bose

[sponce]

You can do both. You will get the same phonon dispersion regardless.

For your 2D question, you will still have an issue even if ultra-dense grid are used if you are using 100x100x1 grids.
The problem is that the el-ph matrix element for small q will be wrongly interpolated. In 3D the matrix element diverge whereas in 2D they go to a finite value.

Best,
Samuel

[anindya@iiita]

Dear Sir,
Please have a look on this paper "ElectronPhonon Interactions and the Intrinsic Electrical Resistivity of Graphene" (link: https://pubs.acs.org/doi/abs/10.1021/nl ... ode=nalefd). This paper shows a2f epw calculation of 2D materials and it has been done in epw already.I am still waiting for a valuable comment from you in this regard.I am looking for some command using which a 2D calculation can be done here.

Thanks and regards,
Anindya Bose