[Pw_forum] NEB calculation, the energies of interpolated images are lower than the IS

[Qianqian Wang]

Dear users,
I'm trying to use pwneb to get the energy barrier for H diffucision. During
the calculation process, the shape of the energy lines are inverse. Anyone
can help me?
This is my input and partical output files. I fixed most of the atom
coordinates during the calculation:
input:
BEGIN
BEGIN_PATH_INPUT
&PATH
  restart_mode      = 'from_scratch'
  string_method     = 'neb',
  nstep_path        = 200,
  ds                = 2.D0,
  opt_scheme        = "broyden",
  num_of_images     = 8,
  k_max             = 0.3D0,
  k_min             = 0.2D0,
  CI_scheme         = "no-CI",
  first_last_opt    = T,
    use_freezing    = T,
  path_thr          = 0.1D0,
/
END_PATH_INPUT
BEGIN_ENGINE_INPUT
&CONTROL
  prefix         = "o2s1"
  outdir         = "/home/qwang/gamma/o2s1",
  pseudo_dir     = "/home/qwang/upf_files",
/
&SYSTEM
  ibrav                  = 0,
  nat                    = 57,
  ntyp                   = 4,
  ecutwfc                = 20.0D0,
  ecutrho                = 200.0D0,
  nspin                  = 1,
  occupations            = "smearing",
  degauss                = 0.02D0,
/
&ELECTRONS
  conv_thr    = 1.D-6,
  mixing_beta = 0.3D0,
/

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 initial path length           =  1.6662 bohr
     initial inter-image distance  =  0.2380 bohr

     string_method                 =    neb
     restart_mode                  =    from_scratch
     opt_scheme                    =    broyden
     num_of_images                 =    8
     nstep_path                    =    200
     CI_scheme                     =    no-CI
     first_last_opt                =    T
     use_freezing                  =    T
     ds                            =    2.0000 a.u.
     k_max                         =    0.3000 a.u.
     k_min                         =    0.2000 a.u.
     suggested k_max               =    0.1542 a.u.
     suggested k_min               =    0.1028 a.u.
     path_thr                      =    0.1000 eV / A

     ------------------------------ iteration   1
------------------------------

   activation energy (->) =   0.074378 eV
     activation energy (<-) =   0.114567 eV

     image        energy (eV)        error (eV/A)        frozen

         1     -31329.3593530            0.206048            T
         2     -31329.3438114            0.674173            F
         3     -31329.3051048            0.880209            F
         4     -31329.2849745            0.889871            F
         5     -31329.2951317            1.007016            F
         6     -31329.3341754            1.005510            F
         7     -31329.3852650            0.751063            F
         8     -31329.3995411            0.268383            T
------------------------------ iteration  11 ------------------------------

     activation energy (->) =   0.000000 eV
     activation energy (<-) =   0.068136 eV

     image        energy (eV)        error (eV/A)        frozen

         1     -31329.3835222            0.702834            F
         2     -31329.3999854            0.245691            T
         3     -31329.4014347            0.421997            T
         4     -31329.4058445            0.119671            T
         5     -31329.4349819            0.211027            T
         6     -31329.4612737            0.874308            F
         7     -31329.4686434            0.332488            T
         8     -31329.4516578            0.601341            F
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20140703/4c1ef6a0/attachment.html>