[Pw_forum] error cannot remap grid on k-point list

[Elena Roxana Margine]

Dear all,

I have been trying to perform an electron-phonon calculation for a hexagonal
structure but the calculation crashes at second point on a 2x2x2 q-mesh in
the elphon subroutine with the error "cannot remap grid on k-point list"  do
n=1,nkh

     do nk=1,nkBZ
        if (eqBZ(nk) == n) go to 20
     end do
     !  this failure of the algorithm may indicate that the displaced grid
     !  (with k1,k2,k3.ne.0) does not have the full symmetry of the lattice
     call errore('lint','cannot remap grid on k-point list',n)
20   continue
  end do

The problem is that the code finds more irreducible k-points than there
should be. In this example k(27) is the same as k(25) and k(29) is the same
as k(9). So, the correct number of k points should be 26 not 30.

     number of k points=   30  gaussian broad. (Ry)=  0.0050     ngauss =
1
                       cart. coord. in units 2pi/a_0
        k(    1) = (   0.0000000   0.0000000   0.0000000), wk =   0.0312500
        k(    2) = (   0.0000000   0.0000000  -0.3048780), wk =   0.0000000
        k(    3) = (   0.0000000   0.0000000   0.1524390), wk =   0.0625000
        k(    4) = (   0.0000000   0.0000000  -0.1524390), wk =   0.0000000
        k(    5) = (   0.0000000   0.0000000  -0.3048780), wk =   0.0312500
        k(    6) = (   0.0000000   0.0000000  -0.6097561), wk =   0.0000000
        k(    7) = (   0.0000000   0.2886751   0.0000000), wk =   0.1875000
        k(    8) = (   0.0000000   0.2886751  -0.3048780), wk =   0.0000000
        k(    9) = (   0.0000000   0.2886751   0.1524390), wk =   0.0937500
        k(   10) = (   0.0000000   0.2886751  -0.1524390), wk =   0.0000000
        k(   11) = (   0.0000000   0.2886751  -0.3048780), wk =   0.1875000
        k(   12) = (   0.0000000   0.2886751  -0.6097561), wk =   0.0000000
        k(   13) = (   0.0000000  -0.5773503   0.0000000), wk =   0.0937500
        k(   14) = (   0.0000000  -0.5773503  -0.3048780), wk =   0.0000000
        k(   15) = (   0.0000000  -0.5773503   0.1524390), wk =   0.1875000
        k(   16) = (   0.0000000  -0.5773503  -0.1524390), wk =   0.0000000
        k(   17) = (   0.0000000  -0.5773503  -0.3048780), wk =   0.0937500
        k(   18) = (   0.0000000  -0.5773503  -0.6097561), wk =   0.0000000
        k(   19) = (   0.2500000   0.4330127   0.0000000), wk =   0.1875000
        k(   20) = (   0.2500000   0.4330127  -0.3048780), wk =   0.0000000
        k(   21) = (   0.2500000   0.4330127   0.1524390), wk =   0.3750000
        k(   22) = (   0.2500000   0.4330127  -0.1524390), wk =   0.0000000
        k(   23) = (   0.2500000   0.4330127  -0.3048780), wk =   0.1875000
        k(   24) = (   0.2500000   0.4330127  -0.6097561), wk =   0.0000000
        k(   25) = (   0.0000000  -0.2886751   0.1524390), wk =   0.0937500
        k(   26) = (   0.0000000  -0.2886751  -0.1524390), wk =   0.0000000
        k(   27) = (   0.0000000  -0.2886751   0.1524390), wk =   0.0937500
        k(   28) = (   0.0000000  -0.2886751  -0.1524390), wk =   0.0000000
        k(   29) = (   0.0000000   0.2886751   0.1524390), wk =   0.0937500
        k(   30) = (   0.0000000   0.2886751  -0.1524390), wk =   0.0000000

These are the input files for this simple test that I can be easily
reproduces.

sic.scf.fit.in
---------------------------
   &control
    calculation = 'scf'
    tstress = .true.
    tprnfor = .true.
    pseudo_dir = './',
    prefix='sic2',
    outdir='./'
    etot_conv_thr = 1.0d-5,
 /
 &system
    ibrav=  4, celldm(1) = 5.81, celldm(3) = 1.64,
    nat=  4, ntyp=3,
    ecutwfc =25.0,ecutrho=200.0,
    occupations='smearing', smearing='methfessel-paxton', degauss=0.005,
    la2F=.true.
 /
 &electrons
    diagonalization='david'
    mixing_mode = 'plain'
    mixing_beta = 0.7
    conv_thr   = 1.0d-8
/
ATOMIC_SPECIES
C   12.011 C.pbe-rrkjus.UPF
Si  28.086 Si.pbe-n-van.UPF
B   10.811 B.pbe-n-van.UPF
ATOMIC_POSITIONS crystal
C        0.666666667   0.333333333   0.500000000
Si       0.000000000   0.000000000   0.375000000
Si       0.666666667   0.333333333   0.875000000
B        0.000000000   0.000000000   0.000000000
K_POINTS automatic
   8 8 8 0 0 0

sic.scf.in
----------------
&control
    calculation = 'scf'
    tstress = .true.
    tprnfor = .true.
    pseudo_dir = './',
    prefix='sic2',
    outdir='./'
    etot_conv_thr = 1.0d-5,
 /
 &system
    ibrav=  4, celldm(1) = 5.81, celldm(3) = 1.64,
    nat=  4, ntyp=3,
    ecutwfc =25.0,ecutrho=200.0,
    occupations='smearing', smearing='methfessel-paxton', degauss=0.005,
 /
 &electrons
    diagonalization='david'
    mixing_mode = 'plain'
    mixing_beta = 0.7
    conv_thr   = 1.0d-8
/
ATOMIC_SPECIES
C   12.011 C.pbe-rrkjus.UPF
Si  28.086 Si.pbe-n-van.UPF
B   10.811 B.pbe-n-van.UPF
ATOMIC_POSITIONS crystal
C        0.666666667   0.333333333   0.500000000
Si       0.000000000   0.000000000   0.375000000
Si       0.666666667   0.333333333   0.875000000
B        0.000000000   0.000000000   0.000000000
K_POINTS automatic
   4 4 4 0 0 0

sic.elph.in
----------------
Electron-phonon coefficients
 &inputph
  tr2_ph=1.0d-10,
  prefix='sic2',
  fildvscf='dv',
  amass(1)=12.011,
  amass(2)=28.086,
  amass(3)=10.811,
  outdir='./',
  fildyn='sic2.dyn',
  elph=.true.,
  trans=.true.,
  ldisp=.true.,
  nq1=2, nq2=2,nq3=2
 /

Thank you,
  Roxana Margine

====================================================
Elena Roxana Margine, Ph.D.
Laboratoire de Physique de la Matière Condensée et Nanostructures
Université Claude Bernard Lyon 1, 43 bd du 11 novembre 1918
69622 Villeurbanne - France    E-mail: rmargine at lpmcn.univ-lyon1.fr
Phone: +33 (0) 4 724 482 37
====================================================
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