inconsistent nscf and elph k-grids

[simba2828]

Dear EPW experts,
I am trying to perform epw calculation but facing an error of "inconsistent nscf and elph k-grids". I have looked into the forum but there is no such error of missing some inverted commas or something else. I am using correct elph q points with grid size 3x3x3 and k-grid 6x6x6. There are total 216 k-points, which I created using kmesh.pl script and there are 6 q-points in phonon calculations. I am attaching the epw input file here.

Code: Select all

--
&inputepw
  prefix      = 'aiida',
  outdir      = './out/'

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

  epwwrite = .true.
  epwread  = .false.

  nbndsub     =  32
  bands_skipped = 'exclude_bands = 1:22'

  wannierize  = .true.
  num_iter    = 500
  dis_froz_max= 17.0
  dis_froz_min= 2.0

  wdata(1)   = 'dis_mix_ratio   = 0.5'
  wdata(2)   = 'dis_num_iter    = 2000'
  wdata(3)    = 'bands_plot : true'
  wdata(4)    = 'bands_num_points : 300'
  wdata(5)    = 'bands_plot_format : xmgrace gnuplot'
  wdata(6)    = 'begin kpoint_path'
  wdata(7)    = 'M 0.5 0.5 0.0 G 0.0 0.0 0.0'
  wdata(8)    = 'G 0.0 0.0 0.0 X 0.5 0.0 0.0'
  wdata(9)    = 'X 0.5 0.0 0.0 M 0.5 0.5 0.0'
  wdata(10)    = 'end kpoint_path'
  wdata(11)   = 'write_tb = true'
  
  iverbosity  = 2

  eps_acustic = 0.1    ! Lowest boundary for the phonon frequency 
  ephwrite    = .true. ! Writes .ephmat files used when Eliasberg = .true.

  nsmear      = 1
  delta_smear = 0.01 ! eV 0.04

  nqstep       = 500

  eliashberg  = .true.

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

  conv_thr_iaxis = 1.0d-4

  temps(1)  = 5
  temps(2)  = 10
  temps(3)  = 12
  temps(4) = 15
  temps(5) = 17
  temps(6) = 20
  temps(7) = 22
  temps(8) = 25
  temps(9) = 8

  nsiter   = 500
  degaussq     = 0.5 ! meV
  degaussw    = 0.04 ! eV ~  1/4 of fsthick
  wscut = 0.2   ! eV 10 times of  Upper limit over frequency integration/summation in the Elisashberg eq(1 cm-1 ~ 1/8000 eV)
  fsthick     = 0.4  ! eV ~ 4 times the maximum phonon frequency 
  muc     = 0.1
  !nswi = 150 

  dvscf_dir   = '../ph/save'
  

  nk1         = 6
  nk2         = 6
  nk3         = 6

  nq1         = 3
  nq2         = 3
  nq3         = 3

  mp_mesh_k = .true.
  nkf1 = 60
  nkf2 = 60
  nkf3 = 60

  nqf1 = 60
  nqf2 = 60
  nqf3 = 60
 /

Thank you in advance for the help.
Shubham

[hpaudya1]

Hi Shubham,

Could you double check your nscf.out file if it has 216 k-points printed or not? Sometimes, because of symmetry, QE prints more number of k-points that the supplied. If it is so, I recommend using 'calculation = 'bands'' instead of 'nscf' in the nscf.in. I hope it helps.

Happy EPWing,
Hari

[simba2828]

Dear Hari,

I checked and there are indeed 216 k-points in the nscf.out. Even after using calculations='bands' I get the same error.
I am using 9x9x9 k-grid and 3x3x3 q-grid in phonon calculations. Also, i was thinking is the issue is with parallelization but I am using no. of cores which are multiple of k and q points both. Can't figure out what is the issue.

Shubham

[simba2828]

Sorry, There are indeed "more than 216 k-points" in the nscf.out. Even after using 'bands', the issue is not solved. I am getting the same error.

[simba2828]

Thank you Hari, It is working now. I was using different nk1, nk2, nk3 while using 'bands' in epw.in.
It is working with 'bands' flag in nscf.in.

[hpaudya1]

Hi Shubham,

That's great.

Happy EPWing,
Hari