Unit of logarithmic average of phonon frequencies

Dear EPW users,

I am interested in electron-phonon interaction in two dimensional materials to understand collective phenomena.
Especially, I want to know the unit of logarithmic average of phonon frequencies in the output of epw, v.4.0.0.
In the output file, logavg = 0.0003401 can be found without unit.
The following are the details of my input and output files.

[code:b9pmoain]
epw
&inputepw
prefix = ‘mote2’
amass(1) = 95.96
amass(2) = 127.6
outdir = ‘./’
time_max = 170000

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

epwwrite = .true.
epwread = .false.

etf_mem = .true.

a2f =.true.
phonselfen = .true.

wannierize = .true.
num_iter = 800
dis_froz_max= 2.5
dis_froz_min= -6.5
dis_win_max= 4.5
dis_win_min= -6.5
proj(1) = ‘Mo:d’
proj(2) = ‘Te:p’

wdata(1) = ‘bands_plot = .true.’
wdata(2) = ‘begin kpoint_path’
wdata(3) = ‘G 0.00 0.00 0.00 Y 0.00 0.50 0.00’
wdata(4) = ‘Y 0.00 0.50 0.00 M 0.50 0.50 0.00’
wdata(5) = ‘M 0.50 0.50 0.00 X 0.50 0.00 0.00’
wdata(6) = ‘X 0.50 0.00 0.00 G 0.00 0.00 0.00’
wdata(7) = ‘G 0.00 0.00 0.00 M 0.50 0.00 0.00’
wdata(8) = ‘end kpoint_path’
wdata(9) = ‘bands_plot_format = gnuplot’
wdata(10) = ‘guiding_centres = true’

iverbosity = 1

parallel_k = .true.
parallel_q = .false.

eps_acustic = 2.0
ephwrite = .true.

fsthick = 0.4 ! eV
eptemp = 300 ! K
degaussw = 0.10 ! eV
nsmear = 1
delta_smear = 0.04 ! eV

degaussq = 0.5 ! meV
nqstep = 500

eliashberg = .true.

laniso = .true.
limag = .true.
lpade = .true.

conv_thr_iaxis = 1.0d-4

wscut = 1.0 ! eV

nstemp = 3
tempsmin = 2.00
tempsmax = 8.00

nsiter = 500

muc = 0.16

dvscf_dir = ‘../save’

nk1 = 4
nk2 = 8
nk3 = 1

nq1 = 4
nq2 = 8
nq3 = 1

nkf1 = 20
nkf2 = 40
nkf3 = 1

nqf1 = 20
nqf2 = 40
nqf3 = 1
/
15 cartesian
0.000000000 0.000000000 0.000000000 0.01
0.000000000 0.227099715 0.000000000 0.02
0.000000000 0.454199430 0.000000000 0.01
0.000000000 0.681299145 0.000000000 0.02
0.000000000 -0.908398861 0.000000000 0.04
0.250000000 0.000000000 0.000000000 0.02
0.250000000 0.227099715 0.000000000 0.02
0.250000000 0.454199430 0.000000000 0.04
0.250000000 0.681299145 0.000000000 0.02
0.250000000 -0.908398861 0.000000000 0.02
-0.500000000 0.000000000 0.000000000 0.04
-0.500000000 0.227099715 0.000000000 0.02
-0.500000000 0.454199430 0.000000000 0.01
-0.500000000 0.681299145 0.000000000 0.02
-0.500000000 -0.908398861 0.000000000 0.01
[/code:b9pmoain]

output is below.

[code:b9pmoain]
.
.
===================================================================
Eliashberg Spectral Function in the Migdal Approximation
===================================================================

 lambda :    2.9539627
 lambda_tr :    2.5730481

 Estimated Allen-Dynes Tc

 logavg =    0.0003401 l_a2F =    2.9830315
 mu =   0.10 Tc =         9.639527937051 K
 mu =   0.12 Tc =         9.325415447053 K
 mu =   0.14 Tc =         9.008365664317 K
 mu =   0.16 Tc =         8.688529631271 K
 mu =   0.18 Tc =         8.366082310892 K
 mu =   0.20 Tc =         8.041225121179 K
 a2F          :      3.52s CPU      3.53s WALL (       1 calls)

 ===================================================================
 Solve anisotropic Eliashberg equations
 ===================================================================


 Finish reading .freq file

              Fermi level (eV) =     1.3528688042E+00
 DOS(states/spin/eV/Unit Cell) =     1.0916033215E+00
        Electron smearing (eV) =     1.0000000000E-01
             Fermi window (eV) =     4.0000000000E-01
 Nr k-points within the Fermi shell =       518 out of       800
       2 bands within the Fermi window

.
.
.
[/code:b9pmoain]

Thank you very much for your time.

Best,
Jun-Ho

Dear Jun-Hu,

Looking in the code the logarithmic average of phonon frequencies is printed in file a2f.f90 (line 178) in the unit of the frequency which is Ryd. If you want to convert it to meV you can change line 178 to

WRITE(stdout,‘(5x,a,f12.7,a,f12.7)’) "logavg = ", logavg(1)*ryd2mev, " l_a2F = ", l_a2F(1)

and recompile the code.

Best,
Roxana

Dear Roxana,

Thank you very much!

Best,
Jun-Ho