EPW Forum

Dear Dr. Samuel

Thank you for your response. I copied the epw.in below.


nbndsub = 4
nbndskip = 0

wannierize = .true.
num_iter = 300
iprint = 2
dis_win_max = 30
dis_win_min = 0
dis_froz_max= 15
dis_froz_min=0
proj(1) = 'Al:sp3'

wdata(1) = 'bands_plot = .true.'
wdata(2) = 'begin kpoint_path'
wdata(3) = 'L 0.50 0.00 0.00 G 0.00 0.00 0.00'
wdata(4) = 'G 0.00 0.00 0.00 X 0.50 0.50 0.00'
wdata(5) = 'X 0.50 0.50 0.00 G 0.00 0.00 0.00'
wdata(6) = 'end kpoint_path'
wdata(7) = 'bands_plot_format = gnuplot'

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

parallel_k = .true.
parallel_q = .false.

fsthick = 1.36056981 ! eV
eptemp = 300 ! K (same as PRB 76, 165108)
degaussw = 0.1 ! eV

dvscf_dir = '../phonons/save'
filukk = './al.ukk'
filqf = 'meshes/path.dat'
nkf1 = 50
nkf2 = 50
nkf3 = 50

nk1 = 6
nk2 = 6
nk3 = 6

nq1 = 6
nq2 = 6
nq3 = 6
/
16 cartesian
0.0000000 0.0000000 0.0000000 0.0092593
0.1178511 -0.1178511 0.1178511 0.0740741
0.2357023 -0.2357023 0.2357023 0.0740741
-0.3535534 0.3535534 -0.3535534 0.0370370
0.0000000 0.0000000 0.2357023 0.0555556
0.1178511 -0.1178511 0.3535534 0.2222222
-0.4714045 0.4714045 -0.2357023 0.2222222
-0.3535534 0.3535534 -0.1178511 0.2222222
-0.2357023 0.2357023 0.0000000 0.1111111
0.0000000 0.0000000 0.4714045 0.0555556
-0.5892557 0.5892557 -0.1178511 0.2222222
-0.4714045 0.4714045 0.0000000 0.1111111
0.0000000 0.0000000 -0.7071068 0.0277778
-0.4714045 0.7071068 -0.2357023 0.2222222
-0.3535534 0.5892557 -0.1178511 0.2222222
0.2357023 0.0000000 -0.7071068 0.1111111


I tried changing fsthick and the corresponding figure when fsthick= 5eV is attached. The change was small for higher values than 5eV

https://drive.google.com/open?id=0B47VtBcBE0CqektKVGNQRTN6RGs



Thank you very much
With Regards

Inoka

Dear Inoka,

I'm afraid I'm not sure I understand what is your problem ?

You seem, from you input, to be trying to plot the imaginary part of the phonon self-energy of Aluminum.

You are trying to compare your results with
- Noffinger 2010, Fig 5(b) ? This figure is the electron (not phonon) self-energy of Graphene.

Your Figure does indeed look a bit strange compare to the Fig 5(f) of the new EPW paper for the phonon self-energy of B-doped diamond.
To understand your result, you need to look at 3 things:
1) Your electronic bandstructure of Al
2) Your phonon bandstructure of Al
3) Where is the Fermi level there.

Based on that you should be able to understand your results by understanding the different scattering mechanism (which eigenstates are connected together via a phonon).

Best,

Samuel

Dear Dr. Samuel

I am sorry for my unclear problem. My requirement is to get electron relaxation time Tau.(Tau=?/2Im(electron Self E))

Thus I tried to plot Im(self E)of Electron Vs (E-Ef) from epw2.out. (also Im(selfE) along k mesh)

For my epw2.in I have given elecselfen = .true. and phonselfen = .fasle.
(The one I copied before is epw.in)

I plotted the data corresponds to the 2nd band as it was (valance band) close to fermi energy. I expected to have something similar to references(Noffinger's or new EPW paper) But I am getting a different one.

Please let me know if my procedure is wrong or if I have misunderstood the code.

Thank you
Inoka

Dear Inoka,

I guess you have a metal (Al)?

It would help if you could show us
1) Your electronic bandstructure of Al
2) Your phonon bandstructure of Al
3) Where is the Fermi level there.

Best,

Samuel

Dear Dr. Samuel

Here I attached the electronic bandstructure (DFT and wannier together) and phonon dispersion curves. Fermi energy is 8.4431 eV and I have wannierized 4 bands with sp3 type projections in the epw calculation. I did it because the valance configuration of Al is 3s2 3p1.

Since I am interested only in electron linewidth, I didnt care about phonon dispersion curve. ( I do not know how to connect it with my study)

https://drive.google.com/open?id=0B47VtBcBE0CqQW9oWFFoNlBrYzQ
https://drive.google.com/open?id=0B47VtBcBE0CqTUFTUUlfVWc2YnM


Please let me know what is wrong with my calculation or what I need to improve.

Thank you
Inoka

Hello Inoka,

It seems like your Wannierzation is quite bad indeed.

I advice you to try to have a good Wannierization using the Wannier90 software directly. You can access the doc at http://www.wannier.org/doc/user_guide.pdf

Once you have a good Wannierzation, you can then use the same parameters in EPW.

You might want to look into frozen windows and disentanglement.

Best,

Samuel