[QE-users] convergence in NEB

[mehrdad zamzamian]

Hi all dear QE users
I want to calculate the vacancy migration in alpha-Fe. I defined 2by2by2
supercell and used NEB but i could not achieve any convergence. searching
in archives did not help. at the end of this message is my input and a part
of the output. I tested various changes like k-point, ds,  num_of_images
... but nothing happened.  Please guide me if possible.
------------------------------------------------------
BEGIN
BEGIN_PATH_INPUT
&PATH
  restart_mode      = 'from_scratch'
  string_method     = 'neb',
  nstep_path        = 50,
  ds                = 1.D0,
  opt_scheme        = "broyden",
  num_of_images     = 12,
  CI_scheme         = "no-CI",
  path_thr          = 0.1,
/
END_PATH_INPUT
BEGIN_ENGINE_INPUT
&CONTROL
  prefix         = ""
  pseudo_dir     = "",
/
&SYSTEM
    a                         =  5.69623e+00
    degauss                   =  1.00000e-02
    ecutrho                   =  2.25000e+02
    ecutwfc                   =  2.50000e+01
    ibrav                     = 1
    nat                       = 15
    nspin                     = 2
    ntyp                      = 1
    occupations               = "smearing"
    smearing                  = "gaussian"
    starting_magnetization(1) =  2.00000e-01
/
&ELECTRONS
  mixing_beta = 0.01
  conv_thr =  1.0d-8
  electron_maxstep=200
/
&IONS
/
ATOMIC_SPECIES
Fe     55.84500  Fe.pbe-nd-rrkjus.UPF
BEGIN_POSITIONS
FIRST_IMAGE
ATOMIC_POSITIONS (angstrom)
Fe      0.000000   0.000000   0.000000
Fe      1.424058   1.424058   1.424058
Fe      0.000000   0.000000   2.848116
Fe      1.424058   1.424058   4.272174
Fe      0.000000   2.848116   0.000000
Fe      1.424058   4.272174   1.424058
Fe      0.000000   2.848116   2.848116
Fe      1.424058   4.272174   4.272174
Fe      2.848116   0.000000   0.000000
Fe      4.272174   1.424058   1.424058
Fe      2.848116   0.000000   2.848116
Fe      4.272174   1.424058   4.272174
Fe      2.848116   2.848116   0.000000
Fe      4.272174   4.272174   1.424058
Fe      2.848116   2.848116   2.848116
LAST_IMAGE
ATOMIC_POSITIONS (angstrom)
Fe      0.000000   0.000000   0.000000
Fe      1.424058   1.424058   1.424058
Fe      0.000000   0.000000   2.848116
Fe      1.424058   1.424058   4.272174
Fe      0.000000   2.848116   0.000000
Fe      1.424058   4.272174   1.424058
Fe      0.000000   2.848116   2.848116
Fe      1.424058   4.272174   4.272174
Fe      2.848116   0.000000   0.000000
Fe      4.272174   1.424058   1.424058
Fe      2.848116   0.000000   2.848116
Fe      4.272174   1.424058   4.272174
Fe      2.848116   2.848116   0.000000
Fe      4.272174   4.272174   1.424058
Fe      4.272174   4.272174   4.272174
END_POSITIONS
K_POINTS (automatic)
 5 5 5 0 0 0
END_ENGINE_INPUT
END
-----------------------------------------------------------------------
  tcpu =      0.4    self-consistency for image   1

     WARNING :  scf convergence NOT achieved on image   1

     cleaning-up extrapolation files
  -----------------------------------------------------------------------
Best regards
S.M.Zamzamian
Iran, Tehran
Sharif University of Technology
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