[QE-users] Mismatch between k-points from scf.out and q-point from system.dyn0

[Ashis Kundu]

Dear all,

Why is there a mismatch between k-points from SCF  and q-point from
system.dyn0 (phonon calculation)?
I have tried many systems before and never face this problem. Ideally they
should be the same. Please let me know if I am doing something wrong.

The k-points generated from SCF

    number of k points=     8  Methfessel-Paxton smearing, width (Ry)=
 0.0200
                       cart. coord. in units 2pi/alat
        k(    1) = (   0.0000000   0.0000000   0.0000000), wk =   0.0740741
        k(    2) = (  -0.3333333   0.0000000   0.0977788), wk =   0.2962963
        k(    3) = (  -0.3333333   0.3333333   0.1955577), wk =   0.5925926
        k(    4) = (   0.3333333   0.3333333  -0.0000000), wk =   0.2962963
        k(    5) = (   0.0000000   0.0000000   0.1955577), wk =   0.1481481
        k(    6) = (   0.6666667   0.0000000  -0.0000000), wk =   0.1481481
        k(    7) = (   0.0000000  -0.3333333  -0.0977788), wk =   0.2962963
        k(    8) = (   0.0000000   0.6666667   0.0000000), wk =   0.1481481

q-point from phonon calculations (a mesh of 3x3x3 is used)

0.00000000 0.00000000 0.00000000
-0.33333333 0.00000000 0.09777884
0.00000000 0.33333333 0.09777884
-0.33333333 0.33333333 0.19555767
0.33333333 0.33333333 -0.00000000
0.00000000 0.00000000 0.19555767
0.66666667 0.00000000 -0.00000000
0.00000000 -0.66666667 -0.00000000

Below are the SCF and phonon input file

scf.in
-----
&control
    calculation     = 'scf'
    prefix          = 'TaP'
    pseudo_dir      = '../pp'
    outdir          = './'
    wf_collect      = .true.
    tprnfor         = .true.
    tstress         = .true.
 /
 &system
    ibrav           = 7
    celldm(1)       = 6.173529611
    celldm(3)       = 3.409054
    nat             = 4
    ntyp            = 2
    ecutwfc         = 100
    occupations     = 'smearing'
    smearing        = 'mp'
    degauss         = 0.02
 /
 &electrons
    diagonalization = 'david'
    mixing_beta     = 0.7
    conv_thr        = 1.0d-10
 /
ATOMIC_SPECIES
  Ta  180.948 Ta.pw-mt_fhi.UPF
  P   30.974  P.pw-mt_fhi.UPF
ATOMIC_POSITIONS {alat}
Ta   0.0000000   0.0000000  -0.0044625
Ta   0.0000000   0.5000000   0.8478074
P    0.0000000   0.0000000   1.4178478
P    0.5000000   0.0000000   0.5655748
K_POINTS {automatic}
 15 15 15  0 0 0

ph.in
----
phonon
&inputph
  prefix   = 'TaP'
  fildyn   = 'TaP.dyn'
  fildvscf = 'dvscf'
  ldisp    = .true.
  epsil    = .false.
  nq1 = 3
  nq2 = 3
  nq3 = 3
  tr2_ph   =  1.0d-14
 /


Best regards,
Ashis
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