EPW Forum

Dear EPW Developers and Users,

Recently, I am calculating the electron-phonon coupling in the 2D MoS2. Following the posts in the EPW forum, I have prepared the input file of epw and calculate the electron-phonon coupling using the EPW-4.1. However, the calculated value is far too large, just like this:

73.5736320 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000
Integrated el-ph coupling
# 295.9530319 300.2090991 306.0841297 312.8515565 319.3059782 324.5751299 328.3089847 330.5235911 331.4169220 331.2457465
Phonon smearing (meV)
# 0.2000000 0.2500000 0.3000000 0.3500000 0.4000000 0.4500000 0.5000000 0.5500000 0.6000000 0.6500000
Electron smearing (eV) 0.0200000
Fermi window (eV) 3.0000000
Summed el-ph coupling 289.8528171

My input file of epw.in is:
--
&inputepw
prefix='mos2',
amass(1)=95.94,
amass(2)=32.085,
outdir = './'

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

etf_mem = .false.

epwwrite = .false.
epwread = .false.

nbndsub = 22
nbndskip = 0

wannierize = .true.
num_iter = 500
!dis_win_max = 50
!dis_win_min = -10
!dis_froz_min= -10
!dis_froz_max= 30
proj(1) = 'Mo:d'
proj(2) = 'S:sp2'

system_2d = .true.

iverbosity = 2
!elinterp = .true.
!phinterp = .true.

!tshuffle2 = .true.
!tphases = .false.

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

parallel_k = .true.
parallel_q = .false.

fsthick = 3! eV
eptemp = 300 ! K
degaussw = 0.02 ! eV
nsmear = 1
delta_smear =0.02

degaussq = 0.2 ! meV
nqstep = 500

efermi_read = .true.
fermi_energy =5.3584 !eV

dvscf_dir = '../phonon/save'
! filqf = 'phon_band.qpt'

nk1 = 16
nk2 = 16
nk3 = 1

nq1 = 8
nq2 = 8
nq3 = 1


nkf1 = 64
nkf2 = 64
nkf3 = 1

nqf1 = 32
nqf2 = 32
nqf3 = 1
/
10 cartesian
....

So what is the potential reason for such large electron-phonon coupling strength and how can I tune the parameters. Any suggestions?

Best,
Amos

Dear Amos,

Just a quick question - have you done some standard checks e.g. the interpolated electron and phonon band structure, and a good decay of the matrix elements?

Carla