2/hbar value

[ysaeed]

hello
I am new to epw and trying to find relaxation time for Si as an example..
I am getting two problem ..
I run successfully epw.in and get correct band structure and phonon, also get linewidth.elself with column 3 and 4 to plot but not get the correct el-ph scattering rate..
what is the value we should used for 2/hbar to multiply with Im part (column 4 in linewidth.elself) ?
How we get it for valence band and conduction band?
Or any one give me the input for Si to compare it...
my epw.in is below
--
&inputepw
prefix = 'si',
amass(1) = 28.0855,
outdir = './'

elph = .true.
! kmaps = .false.
epbwrite = .true.
epbread = .false.

epwwrite = .true.
epwread = .false.

nbndsub = 8
nbndskip = 0

wannierize = .true.
num_iter = 1000
dis_win_max = 17.0d0
! dis_win_min = -3
dis_froz_max = 6.0d0
! dis_froz_min= -3
proj(1) = 'Si:sp3'
wdata(1) = 'bands_plot = .true.'
wdata(2) = 'begin kpoint_path'
wdata(3) = 'G 0.00 0.00 0.00 X 0.00 0.50 0.50'
wdata(4) = 'X 0.00 0.50 0.50 W 0.25 0.50 0.75'
wdata(5) = 'W 0.25 0.50 0.75 L 0.50 0.50 0.50'
wdata(6) = 'L 0.50 0.50 0.50 K 0.375 0.375 0.75'
wdata(7) = 'K 0.375 0.375 0.75 G 0.00 0.00 0.00'
wdata(8) = 'G 0.00 0.00 0.00 L 0.50 0.50 0.50'
wdata(9) = 'end kpoint_path'
wdata(10) = 'bands_plot_format = gnuplot'

iverbosity = 0

elinterp = .true.
phinterp = .true.

tshuffle2 = .true.
tphases = .false.

elecselfen = .true.
phonselfen = .true.

parallel_k = .true.
parallel_q = .false.

fsthick = 15 ! eV
eptemp = 0.0 ! K
degaussw = 1.00 ! eV
!degaussq = 0.05 !meV

a2f = .false.
! eps_acustic = 400
dvscf_dir = '../phonons/save'

nk1 = 6
nk2 = 6
nk3 = 6

nq1 = 6
nq2 = 6
nq3 = 6

nkf1 = 50
nkf2 = 50
nkf3 = 50

nqf1 = 50
nqf2 = 50
nqf3 = 50
/
16 cartesian
0.000000000 0.000000000 0.000000000 0.0092593
-0.166666667 0.166666667 -0.166666667 0.0740741
-0.333333333 0.333333333 -0.333333333 0.0740741
0.500000000 -0.500000000 0.500000000 0.0370370
0.000000000 0.333333333 0.000000000 0.0555556
-0.166666667 0.500000000 -0.166666667 0.2222222
0.666666667 -0.333333333 0.666666667 0.2222222
0.500000000 -0.166666667 0.500000000 0.2222222
0.333333333 0.000000000 0.333333333 0.1111111
0.000000000 0.666666667 0.000000000 0.0555556
0.833333333 -0.166666667 0.833333333 0.2222222
0.666666667 -0.000000000 0.666666667 0.1111111
0.000000000 -1.000000000 0.000000000 0.0277778
0.666666667 -0.333333333 1.000000000 0.2222222
0.500000000 -0.166666667 0.833333333 0.2222222
-0.333333333 -1.000000000 0.000000000 0.1111111
Best
Yasir Saeed

[sponce]

Dear Yasir Saeed,

Thank you for your interest in EPW.

You can find the relationship between imaginary part of the electron-phonon self-energy and the scattering rate in Eq. 61 of http://www.sciencedirect.com/science/ar ... 5516302260

So there should only be a factor 2.

Regarding valence and conduction, the linewidth.elself file should give your the im. sigma for different k-point and bands. You just have to take the band that corresponds to your valence or conduction bands.

Best,

Samuel