[QE-users] EPW error >> Error in routine createkmap (1): q-vec not commensurate

[pboulet]

Hello,

I have read somewhere that the k-point grid and the q-grid have to be commensurate with one another. For instance, if your q-grid is 2x2x2 the k-point one could be 2x2x2, 4x4x4, 8x8x8, 10x10x10, 12x12x12 etc.

HTH,
Pascal


Pascal Boulet
—
Professor in computational materials chemistry - DEPARTMENT OF CHEMISTRY
University of Aix-Marseille - Avenue Escadrille Normandie Niemen - F-13013 Marseille - FRANCE
Tél: +33(0)4 13 55 18 10 - Fax : +33(0)4 13 55 18 50
Email : pascal.boulet at univ-amu.fr <mailto:pascal.boulet at univ-amu.fr>










> Le 19 oct. 2021 à 04:53, 4120109024李晨纲 via users <users at lists.quantum-espresso.org> a écrit :
> 
> Dear researchers：
> Hello, everyone. Let me ask you a question about EPW.
> First，this is the pw, EPW version and phonon version I use：
> 
> Program PWSCF v.6.8 starts on 19Oct2021 at 10:47:42 
> Program EPW v.5.4 starts on 19Oct2021 at 10:41:49
> Program PHONON v.6.8 starts on 19Oct2021 at 10:42:21 
> 
> Now，I am learning to use the BTE method with electroacoustic coupling to calculate the mobility of w-GaN, but the following error occurs in the calculation using Wannier interpolation in “epw1.out" ：
> 
>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>      Error in routine createkmap (1):
>      q-vec not commensurate
>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> 
> 
> My "epw1. In" file is as follows:
> -
> &inputepw
>   prefix      = 'gan'
>   amass(1)    = 69.723
>   amass(2)    = 14.007
>   outdir      = './'
> 
>   iverbosity  = 0
> 
>   elph        = .true.
>   epbwrite    = .true.
>   epbread     = .false.
>   epwwrite    = .true.
>   epwread     = .false.
>   etf_mem     = 1
>   vme         = 'wannier'
> 
>   lpolar      = .true.
>   lifc        = .false.
>   asr_typ     = 'simple'
>   use_ws      = .false.
>   lphase      = .true.
> 
>   nbndsub     =  14
>   bands_skipped = 'exclude_bands = 1-12'
> 
>   wannierize  = .true.
>   num_iter    = 1500
>   iprint      = 3
>   dis_win_max = 25.5
>   dis_win_min = 2.2
>   dis_froz_max= 14.5
>   proj(1)     = 'Ga:sp3'
>   proj(2)     = 'N:p'
>   wdata(1) = 'bands_plot = .true.'
>   wdata(2) = 'begin kpoint_path'
>   wdata(3) = 'G 0.00 0.00 0.00 M 0.50 0.00 0.00'
>   wdata(4) = 'G 0.00 0.00 0.00 K 0.33333333333 0.33333333333 0.00'
>   wdata(5) = 'G 0.00 0.00 0.00 A 0.00 0.00 0.50'
>   wdata(6) = 'end kpoint_path'
>   wdata(7) = 'bands_plot_format = gnuplot'
>   wdata(8) = 'guiding_centres = .true.'
>   wdata(9) = 'dis_num_iter      = 1000'
>   wdata(10) = 'num_print_cycles  = 10'
>   wdata(11) = 'dis_mix_ratio     = 1.0'
>   wdata(12) = 'conv_tol = 1E-8'
>   wdata(13) = 'conv_window = 4'
> 
>   elecselfen  = .false.
>   phonselfen  = .false.
>   a2f         = .false.
> 
>   fsthick     = 100.0 ! eV
>   temps       = 1 ! K
>   degaussw    = 0.01 ! eV
> 
>   dvscf_dir   = './save/'
> 
>   efermi_read = .true
>   fermi_energy= 11.80
>   band_plot   = .true.
> 
>   filkf       = './MGA.txt'
>   nqf1        = 1
>   nqf2        = 1
>   nqf3        = 1
> 
>   nk1         = 2
>   nk2         = 2
>   nk3         = 2
>   nq1         = 4
>   nq2         = 4
>   nq3         = 4
>  /
>                              
> I have ensured that my phonon calculation uses a 4x4x4 grid and that the nscf calculation uses a 2x2x2 path. The following are the inputs of these two files
> 
> 
> ---
>  &inputph
>   tr2_ph=1.0d-14,
>   prefix='gan',
>   amass(1)=69.723,
>   amass(2)=14.007,
>   outdir='./',
>   fildyn='gan.dyn',
>   fildvscf='dvscf'
>   ldisp=.true.,
>   epsil=.true.,
>   nq1=4, nq2=4, nq3=4
>  /
> 
> 
> &control
>     calculation='nscf'
>     prefix='gan'
>     restart_mode='from_scratch'
>     pseudo_dir='./'
>     outdir='./'
>     tprnfor=.true.
>     tstress=.true.
>     wf_collect = .true.
>     verbosity = 'high'
>  /
>  &system
>     ibrav    = 4
>     celldm(1)= 5.9612
>     celldm(3)= 1.6299
>     nat      = 4
>     ntyp     = 2
>     ecutwfc  = 40
>     nbnd     = 30
>  /
>  &electrons
>     diagonalization='david'
>     mixing_beta=0.7
>     conv_thr=1.0d-10
>     diago_full_acc = .true.
>  /
> ATOMIC_SPECIES
>   Ga  69.723   Ga-LDA.upf
>   N   14.007   N-LDA.upf
> ATOMIC_POSITIONS crystal
>   Ga  0.666666666667 0.333333333333  0.0
>   N   0.666666666667 0.333333333333  0.376458
>   Ga  0.333333333333 0.666666666667  0.5
>   N   0.333333333333 0.666666666667  0.876458
> K_POINTS crystal
> 8
> 0.0   0.0   0.0   0.125
> 0.0   0.0   0.5   0.125
> 0.0   0.5   0.0   0.125
> 0.0   0.5   0.5   0.125
> 0.5   0.0   0.0   0.125
> 0.5   0.0   0.5   0.125
> 0.5   0.5   0.0   0.125
> 0.5   0.5   0.5   0.125
> 
> 
> Thank you for your attention and look forward to your answers！！！
> 
> 
> 
> 
> 
> 
> 
> 
> 
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