Nonphysical values of self-energy

[dinesh169]

Hello,

I am using QE 6.2 and epw 4.3. I am studying WSe2 single layer with spin orbit coupling (SOC). Here is my input epw file

###################################################--
&inputepw
prefix = 'wse2'
amass(1) = 183.84,
amass(2) = 78.96,
outdir = './'

restart = .true.
restart_freq = 5000

max_memlt = 5.0
elph = .true.
epbwrite = .true.
epbread = .false.

epwwrite = .true.
epwread = .false.

nbndsub = 22
nbndskip = 4

kmaps = .false.

wannierize = .true.
num_iter = 8000
iprint = 2
dis_win_max = 30
dis_win_min = -30
dis_froz_min = -7.5
dis_froz_max= 8.4

proj(1) = 'W:d'
proj(2) = 'Se:p'


wdata(1) = 'bands_plot = true'
wdata(2) = 'begin kpoint_path'
wdata(3) = 'G 0.0000000 0.0000000 0.0000000 K 0.6666667 -0.3333333 0.000000'
wdata(4) = 'K 0.6666667 -0.3333333 0.0000000 M 0.5000000 -0.5000000 0.000000'
wdata(5) = 'M 0.5000000 -0.5000000 0.0000000 G 0.0000000 0.0000000 0.000000'
wdata(6) = 'end kpoint_path'
wdata(7) = 'conv_window = 2'
wdata(8) = 'num_print_cycles = 50'
wdata(9) = 'conv_tol = 1.0E-10'
wdata(10)= 'dis_conv_tol = 1.0E-10'
wdata(11)= 'dis_mix_ratio = 0.5'
wdata(12)= 'dis_num_iter = 8000'
wdata(13) = 'search_shells = 48'

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

parallel_k = .true.
parallel_q = .false.

eptemp = 00 ! K (same as PRB 76, 165108)
degaussw = 0.01 ! eV
fsthick = 5.0

dvscf_dir = '../save'
filukk = './wse2.ukk'


nkf1 = 100
nkf2 = 100
nkf3 = 1

nqf1 = 100
nqf2 = 100
nqf3 = 1

nk1 = 12
nk2 = 12
nk3 = 1

nq1 = 12
nq2 = 12
nq3 = 1
/
19 cartesian
0.0000000 0.0000000 0.0000000 0.0138889
0.0000000 0.0962250 0.0000000 0.0833333
0.0000000 0.1924501 0.0000000 0.0833333
#########################################################
so i get the following self-energy values


ik = 1 coord.: 0.0000000 0.0000000 0.0000000
-------------------------------------------------------------------
E( 3 )= -3.2839 eV Re[Sigma]= -40.370417 meV Im[Sigma]= 27.773861 meV Z= 0.931765 lam= 0.073232
E( 4 )= -3.2839 eV Re[Sigma]= -40.370417 meV Im[Sigma]= 27.773861 meV Z= 0.931765 lam= 0.073232
E( 5 )= -3.2677 eV Re[Sigma]= -32.849332 meV Im[Sigma]= 34.035052 meV Z= 0.597428 lam= 0.673843
E( 6 )= -3.2677 eV Re[Sigma]= -32.849332 meV Im[Sigma]= 34.035052 meV Z= 0.597428 lam= 0.673843
E( 7 )= -2.9244 eV Re[Sigma]= -5.203599 meV Im[Sigma]= 36.956137 meV Z= 0.923543 lam= 0.082787
E( 8 )= -2.9244 eV Re[Sigma]= -5.203599 meV Im[Sigma]= 36.956137 meV Z= 0.923543 lam= 0.082787
E( 9 )= -2.2316 eV Re[Sigma]= 32.436204 meV Im[Sigma]= 48.198527 meV Z= 1.092799 lam= -0.084919
E( 10 )= -2.2316 eV Re[Sigma]= 32.436204 meV Im[Sigma]= 48.198527 meV Z= 1.092799 lam= -0.084919
E( 11 )= -1.7801 eV Re[Sigma]= 13.947887 meV Im[Sigma]= 30.448463 meV Z= 0.905908 lam= 0.103865
E( 12 )= -1.7801 eV Re[Sigma]= 13.947887 meV Im[Sigma]= 30.448463 meV Z= 0.905908 lam= 0.103865
E( 13 )= -1.3104 eV Re[Sigma]= 32.315769 meV Im[Sigma]= 14.881246 meV Z= 0.872832 lam= 0.145695
E( 14 )= -1.3104 eV Re[Sigma]= 32.315769 meV Im[Sigma]= 14.881246 meV Z= 0.872832 lam= 0.145695
E( 15 )= 2.0035 eV Re[Sigma]= 22.117341 meV Im[Sigma]= 66.485642 meV Z= 1.620459 lam= -0.382891
E( 16 )= 2.0035 eV Re[Sigma]= 22.117341 meV Im[Sigma]= 66.485642 meV Z= 1.620459 lam= -0.382891
E( 17 )= 2.2388 eV Re[Sigma]= 30.231269 meV Im[Sigma]= 43.587512 meV Z= 1.184063 lam= -0.155451
E( 18 )= 2.2388 eV Re[Sigma]= 30.231269 meV Im[Sigma]= 43.587512 meV Z= 1.184063 lam= -0.155451
E( 19 )= 2.2448 eV Re[Sigma]= 29.510011 meV Im[Sigma]= 40.221370 meV Z= 1.246386 lam= -0.197680
E( 20 )= 2.2448 eV Re[Sigma]= 29.510011 meV Im[Sigma]= 40.221370 meV Z= 1.246386 lam= -0.197680
E( 21 )= 2.4860 eV Re[Sigma]= 22.392284 meV Im[Sigma]= 28.168167 meV Z= 1.140666 lam= -0.123320
E( 22 )= 2.4860 eV Re[Sigma]= 22.392284 meV Im[Sigma]= 28.168167 meV Z= 1.140666 lam= -0.123320
-------------------------------------------------------------------


ik = 2 coord.: 0.0000000 0.0100000 0.0000000
-------------------------------------------------------------------
E( 3 )= -3.2868 eV Re[Sigma]= -39.972182 meV Im[Sigma]= 29.270373 meV Z= 0.960653 lam= 0.040959
E( 4 )= -3.2868 eV Re[Sigma]= -38.743507 meV Im[Sigma]= 26.646225 meV Z= 0.895073 lam= 0.117227
E( 5 )= -3.2688 eV Re[Sigma]= -32.115524 meV Im[Sigma]= 32.960220 meV Z= 0.657217 lam= 0.521567
E( 6 )= -3.2687 eV Re[Sigma]= -31.805083 meV Im[Sigma]= 33.937155 meV Z= 0.565306 lam= 0.768954
E( 7 )= -2.9270 eV Re[Sigma]= -4.952384 meV Im[Sigma]= 37.247632 meV Z= 0.954488 lam= 0.047683
E( 8 )= -2.9268 eV Re[Sigma]= -5.007345 meV Im[Sigma]= 38.235578 meV Z= 0.938476 lam= 0.065558
E( 9 )= -2.2319 eV Re[Sigma]= 35.026202 meV Im[Sigma]= 46.441469 meV Z= 1.058748 lam= -0.055489
E( 10 )= -2.2319 eV Re[Sigma]= 29.277352 meV Im[Sigma]= 50.532035 meV Z= 1.110359 lam= -0.099391
E( 11 )= -1.7820 eV Re[Sigma]= 13.452347 meV Im[Sigma]= 30.853456 meV Z= 0.944077 lam= 0.059236
E( 12 )= -1.7819 eV Re[Sigma]= 14.768175 meV Im[Sigma]= 30.722719 meV Z= 0.930564 lam= 0.074617
E( 13 )= -1.3107 eV Re[Sigma]= 32.406243 meV Im[Sigma]= 14.827708 meV Z= 0.865201 lam= 0.155801
E( 14 )= -1.3107 eV Re[Sigma]= 32.406243 meV Im[Sigma]= 14.827708 meV Z= 0.865201 lam= 0.155801
E( 15 )= 2.0027 eV Re[Sigma]= 20.279614 meV Im[Sigma]= 64.836243 meV Z= 1.596265 lam= -0.373538
E( 16 )= 2.0028 eV Re[Sigma]= 23.409434 meV Im[Sigma]= 67.513669 meV Z= 1.447514 lam= -0.309160
E( 17 )= 2.2311 eV Re[Sigma]= 30.927706 meV Im[Sigma]= 39.386113 meV Z= 0.941151 lam= 0.062528
E( 18 )= 2.2313 eV Re[Sigma]= 29.838445 meV Im[Sigma]= 38.762087 meV Z= 0.923844 lam= 0.082434
E( 19 )= 2.2430 eV Re[Sigma]= 28.702013 meV Im[Sigma]= 38.870878 meV Z= 1.124915 lam= -0.111044
E( 20 )= 2.2430 eV Re[Sigma]= 29.648635 meV Im[Sigma]= 41.531536 meV Z= 1.174804 lam= -0.148794
E( 21 )= 2.4826 eV Re[Sigma]= 21.735881 meV Im[Sigma]= 28.607089 meV Z= 1.247857 lam= -0.198626
E( 22 )= 2.4826 eV Re[Sigma]= 21.734533 meV Im[Sigma]= 29.399005 meV Z= 1.261806 lam= -0.207485


but on changing the fine k/q grids from 100x100 to 300x300, I get the following self-energies
############## fine grids 300x300 ###################
ik = 1 coord.: 0.0000000 0.0000000 0.0000000
-------------------------------------------------------------------
E( 3 )= -3.2843 eV Re[Sigma]= -5990.979257 meV Im[Sigma]= 4324.591187 meV Z= -0.149546 lam= -7.686885
E( 4 )= -3.2843 eV Re[Sigma]= -5990.979257 meV Im[Sigma]= 4324.591187 meV Z= -0.149546 lam= -7.686885
E( 5 )= -3.2680 eV Re[Sigma]= -4817.630938 meV Im[Sigma]= 6413.879220 meV Z= 0.029877 lam= 32.470079
E( 6 )= -3.2680 eV Re[Sigma]= -4817.630938 meV Im[Sigma]= 6413.879220 meV Z= 0.029877 lam= 32.470079
E( 7 )= -2.9248 eV Re[Sigma]= -982.474317 meV Im[Sigma]= 5341.432174 meV Z= 0.109404 lam= 8.140469
E( 8 )= -2.9248 eV Re[Sigma]= -982.474317 meV Im[Sigma]= 5341.432174 meV Z= 0.109404 lam= 8.140469
E( 9 )= -2.2320 eV Re[Sigma]= 4727.623897 meV Im[Sigma]= 6635.298415 meV Z= 0.290749 lam= 2.439396
E( 10 )= -2.2320 eV Re[Sigma]= 4727.623897 meV Im[Sigma]= 6635.298415 meV Z= 0.290749 lam= 2.439396
E( 11 )= -1.7805 eV Re[Sigma]= 1961.812460 meV Im[Sigma]= 4411.156160 meV Z= 0.078874 lam= 11.678437
E( 12 )= -1.7805 eV Re[Sigma]= 1961.812460 meV Im[Sigma]= 4411.156160 meV Z= 0.078874 lam= 11.678437
E( 13 )= -1.3108 eV Re[Sigma]= 4705.010347 meV Im[Sigma]= 2207.925897 meV Z= 0.070441 lam= 13.196260
E( 14 )= -1.3108 eV Re[Sigma]= 4705.010347 meV Im[Sigma]= 2207.925897 meV Z= 0.070441 lam= 13.196260
E( 15 )= 2.0032 eV Re[Sigma]= 3417.349953 meV Im[Sigma]= 9579.042497 meV Z= -0.041814 lam= -24.915696
E( 16 )= 2.0032 eV Re[Sigma]= 3417.349953 meV Im[Sigma]= 9579.042497 meV Z= -0.041814 lam= -24.915696
E( 17 )= 2.2384 eV Re[Sigma]= 4675.855419 meV Im[Sigma]= 5907.027567 meV Z= -0.370271 lam= -3.700721
E( 18 )= 2.2384 eV Re[Sigma]= 4675.855419 meV Im[Sigma]= 5907.027567 meV Z= -0.370271 lam= -3.700721
E( 19 )= 2.2444 eV Re[Sigma]= 4545.468945 meV Im[Sigma]= 5310.455851 meV Z= -0.236033 lam= -5.236701
E( 20 )= 2.2444 eV Re[Sigma]= 4545.468945 meV Im[Sigma]= 5310.455851 meV Z= -0.236033 lam= -5.236701
E( 21 )= 2.4856 eV Re[Sigma]= 3192.664769 meV Im[Sigma]= 3448.966196 meV Z= 0.175098 lam= 4.711101
E( 22 )= 2.4856 eV Re[Sigma]= 3192.664769 meV Im[Sigma]= 3448.966196 meV Z= 0.175098 lam= 4.711101
-------------------------------------------------------------------

ik = 4 coord.: 0.0000000 0.0100000 0.0000000
-------------------------------------------------------------------
E( 3 )= -3.2872 eV Re[Sigma]= -6004.348043 meV Im[Sigma]= 4358.300689 meV Z= 3.922639 lam= -0.745070
E( 4 )= -3.2871 eV Re[Sigma]= -5819.616610 meV Im[Sigma]= 4078.785152 meV Z= 0.169899 lam= 4.885857
E( 5 )= -3.2691 eV Re[Sigma]= -5006.178453 meV Im[Sigma]= 5815.976595 meV Z= 0.033848 lam= 28.544246
E( 6 )= -3.2691 eV Re[Sigma]= -4480.267147 meV Im[Sigma]= 6783.189326 meV Z= 0.025993 lam= 37.471739
E( 7 )= -2.9274 eV Re[Sigma]= -892.412705 meV Im[Sigma]= 5347.484684 meV Z= 0.138532 lam= 6.218548
E( 8 )= -2.9271 eV Re[Sigma]= -1021.097519 meV Im[Sigma]= 5411.329188 meV Z= 0.101229 lam= 8.878640
E( 9 )= -2.2323 eV Re[Sigma]= 5108.255817 meV Im[Sigma]= 6458.741256 meV Z= 0.530864 lam= 0.883722
E( 10 )= -2.2323 eV Re[Sigma]= 4276.294070 meV Im[Sigma]= 6914.714182 meV Z= 0.247112 lam= 3.046748
E( 11 )= -1.7824 eV Re[Sigma]= 1890.548889 meV Im[Sigma]= 4420.085138 meV Z= 0.082294 lam= 11.151575
E( 12 )= -1.7823 eV Re[Sigma]= 2079.118720 meV Im[Sigma]= 4398.682019 meV Z= 0.068536 lam= 13.590815
E( 13 )= -1.3111 eV Re[Sigma]= 4714.883978 meV Im[Sigma]= 2211.738460 meV Z= 0.070424 lam= 13.199634
E( 14 )= -1.3111 eV Re[Sigma]= 4714.883978 meV Im[Sigma]= 2211.738460 meV Z= 0.070424 lam= 13.199634
E( 15 )= 2.0024 eV Re[Sigma]= 3188.267530 meV Im[Sigma]= 9277.938577 meV Z= -0.048593 lam= -21.579217
E( 16 )= 2.0024 eV Re[Sigma]= 3609.354598 meV Im[Sigma]= 9922.434314 meV Z= -0.036890 lam= -28.107983
E( 17 )= 2.2308 eV Re[Sigma]= 4788.161865 meV Im[Sigma]= 5918.601182 meV Z= -0.315556 lam= -4.169008
E( 18 )= 2.2309 eV Re[Sigma]= 4604.235869 meV Im[Sigma]= 5865.724863 meV Z= -0.288795 lam= -4.462663
E( 19 )= 2.2426 eV Re[Sigma]= 4417.588405 meV Im[Sigma]= 5246.945609 meV Z= -0.228146 lam= -5.383166
E( 20 )= 2.2426 eV Re[Sigma]= 4578.745600 meV Im[Sigma]= 5574.655366 meV Z= -0.158954 lam= -7.291133
E( 21 )= 2.4822 eV Re[Sigma]= 3182.746188 meV Im[Sigma]= 3462.947747 meV Z= -1.621053 lam= -1.616883
E( 22 )= 2.4822 eV Re[Sigma]= 3190.247309 meV Im[Sigma]= 3544.475730 meV Z= -2.193261 lam= -1.455942
-------------------------------------------------------------------
I thought the reason might be insufficient memory but it turned out not to be the case. In past did similar calculations on other systems and it worked fine without any nonphysical results. The Wannier spread is around 2.3 Ang^2. I plotted the interpolated phonon band structure (with SOC) and it looks fine as well.

I don't understand the reason of these nonphysical values.
Could you please give some suggestions? what went wrong?

Thank you very much in advance.

Best wishes,

[sponce]

Hello dinesh169,

The only change you made is the fine grids ?
It seems something else changed. Indeed if I look at the eigen-energies at \Gamma they should be exactly the same (the eigen-energies do not depend on the q-point grid and \Gamma-point is contained in both grids).
I can see E( 22 )= 2.4860 eV for the 100 grid and E( 22 )= 2.4856 eV

Therefore something else must be going on.
Are both grid "restart" from reading the epmatwp file ?

Best wishes,
Samuel

[dinesh169]

Hello Samuel,

Thank you very much fro your reply.

The only difference in both the input files are fine k/q grids. I did more check to have some insight of the error.

I noticed, with verbosity =3, the linewidth in epw.out and sum of linewidth over \phonon_mode in linewidth,elself are different.

As you can see below

Electron lifetime (meV)
# ik ibnd E(ibnd) imode Im(Sgima)(meV)
1 1 -0.71245647690430E+01 1 0.15818536008411E+00
1 1 -0.71245647690430E+01 2 0.15441195380855E+00
1 1 -0.71245647690430E+01 3 0.15777675536464E+00
1 1 -0.71245647690430E+01 4 0.11661064433840E-02
1 1 -0.71245647690430E+01 5 0.28857898895064E-02
1 1 -0.71245647690430E+01 6 0.32296676688679E+01
1 1 -0.71245647690430E+01 7 0.67847497987624E-01
1 1 -0.71245647690430E+01 8 0.14888555489852E+00
1 1 -0.71245647690430E+01 9 0.10021328715551E+00


ik = 1 coord.: 0.0000000 0.0000000 0.0000000
-------------------------------------------------------------------
E( 1 )= -7.1246 eV Re[Sigma]= -2379.860809 meV Im[Sigma]= 578.867980 meV Z= -13.918944 lam= -1.071845

What is the maximum number of bands that can be included in the calculations. I am using 22 bands, its it high for the code. When i reduce the bands and energy window then the wannierization goes bad.
Do you think the error happen while summing the linewidth? How can it be avoided?

####### restart issue#########
For temperature 0K calculations finish in one run but for 300K I have to run it twice and calculations are restated from wse2.sigma_restart1 not from wse2.epmatwp1.

Best wishes,