monolayer LiC6 gap distribution

Hello,

I have performed EPW calculations for monolayer LiC6 for which Roxana Margine kindly shared her input with me.

I have several questions regarding the obtained result.

First of all I want to note that my run has crashed at the temperature of 5.1 K with the following error message:

Convergence was not reached in nsiter = 150

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Error in routine sum_eliashberg_aniso_iaxis (1):

increase nsiter or reduce conv_thr_iaxis

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Even though I can indeed increase the number of iterations I don't really believe it will converge. So could you please tell me if there is a different remedy for it?

Since some of the temperatures ran smoothly I could already try to compare some results.

As the benchmark naturally I used the Roxana's paper on LiC6 and in particular the gap vs temperature graph. (link to the image

https://ibb.co/kmKLVwq)

When I plot my gap distribution file called "graphene.imag_aniso_gap0_002.00" which contains information for T = 2 K I get something that is different from the picture in the article (link to the picture

https://ibb.co/CwKBX3N) . The shape is different and the gap barely reaches 0.8 meV whereas the article version is more or less centered around 0.8 meV. Could you plese give me a hint where I might have made a mistake?

Here is my input just in case:

**Code:**

epwcalculation

&inputepw

prefix = 'graphene',

amass(1) = 12.01078

amass(2) = 6.941

outdir = './'

dvscf_dir = '../phonons/save/'

ep_coupling = .true. !run eph calculation

elph = .true. !calculate eph coefficients

kmaps = .false. !Generate the map k+q --> k for folding the rotation matrix U(k+q). Set to "false" to calculate it, "true" to read it

epbwrite = .true. !If epbwrite = .true., the electron-phonon matrix elements

epbread = .false. ! in the coarse Bloch representation and relevant data (dyn

! matrices) are written to disk.

epwwrite = .true. ! If epwwrite = .true., the electron-phonon matrix elements

! in the coarse Wannier representation and relevant data (dyn

! matrices) are written to disk.

! Each pool reads the same file.

epwread = .false. ! If epwread = .true., the electron-phonon matrix elements

! in the coarse Wannier representation are read from the 'epwdata.fmt' and 'XX.epmatwpX' files.

! Each pool reads the same file. It is used for a restart calculation and requires kmaps = .true.

! A prior calculation with epwwrite = .true is also required.

etf_mem = 1 ! If etf_mem == 0, then all the fine Bloch-space el-ph matrix elements

! are store in memory (faster).

! When etf_mem == 1, more IO (slower) but less memory is required.

! When etf_mem == 2, an additional loop is done on mode for the fine grid interpolation

! part. This reduces the memory further by a factor "nmodes".

nbndsub = 15 !Number of wannier functions to utilize.

nbndskip = 1 ! The number of bands lying below the disentanglement

!window in the calculation of the Wannier functions.

!This quantity is necessary to correctly determine

!the Fermi energy.

wannierize = .true.

num_iter = 2000

dis_win_min = -20.0

dis_froz_min = -20.0

dis_froz_max = 2.45

proj(1) = 'f=0.333301340,0.000000000,0.000000000:sp2,pz'

proj(2) = 'f=0.666698660,0.000000000,0.000000000:pz'

proj(3) = 'f=0.000000000,0.333301340,0.000000000:sp2,pz'

proj(4) = 'f=0.333301340,0.333301340,0.000000000:pz'

proj(5) = 'f=0.000000000,0.666698660,0.000000000:pz'

proj(6) = 'f=0.666698660,0.666698660,0.000000000:sp2,pz'

wdata(1) = 'dis_num_iter = 5000'

wdata(2) = 'dis_mix_ratio = 0.9'

wdata(3) = 'guiding_centres = .true.'

wdata(4) = 'bands_plot = true'

wdata(5) = 'begin kpoint_path'

wdata(6) = 'G 0.000000000 0.000000000 0.000000000 M 0.500000000 0.000000000 0.000000000'

wdata(7) = 'M 0.500000000 0.000000000 0.000000000 K 0.333333333 0.333333333 0.000000000'

wdata(8) = 'K 0.333333333 0.333333333 0.000000000 G 0.000000000 0.000000000 0.000000000'

wdata(9) = 'end kpoint_path'

wdata(10) = 'num_print_cycles = 50'

iverbosity = 2

!elinterp = .true.

!phinterp = .true.

!tshuffle2 = .true.

!tphases = .false.

!parallel_k = .true.

! parallel_q = .false.

eps_acustic = 5.0

ephwrite = .true. ! originally .false.

eliashberg = .true.

fsthick = 0.4 ! eV / Energy window around the Fermi level that is taken into account

eptemp = 300 ! Array of smearing occupations for the Fermi occupation in [K].

degaussw = 0.10 ! eV Smearing in the energy-conserving delta functions in [eV]

nsmear = 1 !Number of different smearings used to calculate

! the phonon self-energy

delta_smear = 0.04 ! eV Change in the energy for each additional smearing in the

! phonon self-energy in [eV]

degaussq = 0.5 ! meV Smearing for sum over q in the e-ph coupling in [meV]

nqstep = 500 ! Number of steps used to calculate the a2f

delta_qsmear = 0.1 ! meV Change in the energy for each additional smearing in the a2f in [meV].

dvscf_dir = './save'

laniso = .true.

limag = .true.

lpade = .true. ! originally commented out

conv_thr_iaxis = 1.0d-3

max_memlt = 16.0 ! maximum memory per pool

wscut = 0.6348209988

! gap_edge = 0.0005

nstemp = 12

temps(1) = 2.00

temps(2) = 2.50

temps(3) = 3.00

temps(4) = 3.50

temps(5) = 4.00

temps(6) = 4.50

temps(7) = 5.00

temps(8) = 5.10

temps(9) = 5.20

temps(10) = 5.30

temps(11) = 5.40

temps(12) = 5.50

nsiter = 150

muc = 0.16

nk1 = 12

nk2 = 12

nk3 = 1

nq1 = 6

nq2 = 6

nq3 = 1

mp_mesh_k = .true.

nkf1 = 120

nkf2 = 120

nkf3 = 1

nqf1 = 60

nqf2 = 60

nqf3 = 1

/

7 cartesian

0.000000000 0.000000000 0.000000000 0.055555556

0.000000000 0.192450090 0.000000000 0.333333333

0.000000000 0.384900179 0.000000000 0.333333333

0.000000000 -0.577350269 0.000000000 0.166666667

0.166666667 0.288675135 0.000000000 0.333333333

0.166666667 0.481125224 0.000000000 0.666666667

0.333333333 0.577350269 0.000000000 0.111111111