[Pw_forum] Non converging neb calculation

Korir Kiptiemoi koriro1208 at gmail.com
Sun Nov 18 23:38:07 CET 2012


Dear QE community,
I am interested in studying oxygen vacancy diffusion  in ZnO  and for this reason I performed neb calculation using the input attached, but for some reasons I don't understand, the system does not converge even though the initial and final states   optimized beforehand. Furthermore, the choice of vacancy position were made in such that they correspond to first neighbor oxygen atoms in ZnO.   Attached are  input and  output files.

Kindly assist in  addressing  this problem.


Regards
…………………………….
Korir Kiprono
Polytechnic of Turin 
Italy


BEGIN
BEGIN_PATH_INPUT
&PATH
  restart_mode      = 'from_scratch'
  string_method     = 'neb',
  nstep_path        = 400,
  ds                = 1.D0,
  opt_scheme        = "broyden",
  num_of_images     = 11,
  k_max             = 0.1D0,
  k_min             = 0.05D0,
  first_last_opt    = .true.,
  CI_scheme         = "auto",
  path_thr          = 0.05D0,
/
END_PATH_INPUT
BEGIN_ENGINE_INPUT
&CONTROL
  prefix                = "ZnO_Ovac",
  outdir                = "./tmp",
  pseudo_dir            = "./",
/
&SYSTEM
  ibrav                  = 0,
  celldm(1)              = 12.42108529,
  nat                    = 31,
  ntyp                   = 2,
  ecutwfc                = 28.0D0,
  ecutrho                = 280.0D0,
  occupations            ='smearing',
  smearing               ='gaussian',
  degauss                = 0.005,
/
&ELECTRONS
  conv_thr    = 1.D-8,
  mixing_beta = 0.3D0,
/
&IONS
/
ATOMIC_SPECIES
Zn  65.39     Zn.pbe-van_ak.UPF
 O   15.99     O.pbe-van_ak.UPF
BEGIN_POSITIONS
FIRST_IMAGE
ATOMIC_POSITIONS {angstrom }
Zn       0.000000000   0.000000000  -0.000901300
O        0.000000000   0.000000000   1.982166429
Zn       1.618166296   0.934248744   2.660882286
O        1.587537112   0.916564976   4.668341083
Zn       0.000000000   0.000000000   5.549324230
Zn       1.510731530   0.872221253   7.785147076
O        1.614761747   0.932283127   9.789420866
Zn      -1.647149135   2.813900718  -0.034865746
O       -1.647131851   2.813910697   1.979064959
Zn       0.000000002   3.764882713   2.578931174
O        0.000000002   3.764882713   4.586148646
Zn      -1.624551499   2.826947470   5.242777187
O       -1.641528837   2.817145598   7.246106096
Zn       0.000000002   3.764882713   7.873821255
O        0.000000002   3.764882713   9.870733921
Zn       3.260484073   0.019522635  -0.034865746
O        3.260484073   0.019502678   1.979064959
Zn       4.902801854   0.934248744   2.660882286
O        4.933431038   0.916564976   4.668341083
Zn       3.260484073  -0.006570867   5.242777187
O        3.260484073   0.013032875   7.246106096
Zn       5.010236620   0.872221253   7.785147076
O        4.906206403   0.932283127   9.789420866
Zn       1.647149135   2.813900718  -0.034865746
O        1.647131851   2.813910697   1.979064959
Zn       3.260484075   3.778826580   2.660882286
O        3.260484075   3.814194115   4.668341083
Zn       1.624551499   2.826947470   5.242777187
O        1.641528837   2.817145598   7.246106096
Zn       3.260484075   3.902881561   7.785147076
O        3.260484075   3.782757814   9.789420866
LAST_IMAGE
ATOMIC_POSITIONS {angstrom }
Zn       0.119469042   0.068975484  -0.085296951
O        0.015207179   0.008779869   1.918954244
Zn       1.630247715   0.941223955   2.620686267
O        1.630247715   0.941223955   4.604032865
Zn       0.012421523   0.007171570   5.284174983
O        0.042886882   0.024760753   7.291900841
Zn       1.630247715   0.941223955   8.172918735
Zn      -1.630247713   2.823671869   0.005029795
O       -1.630247713   2.823671869   2.001908162
Zn       0.017145427   3.774794739   2.588903716
O        0.016953247   3.774683784   4.602875645
Zn      -1.630247713   2.823671869   5.202337904
O       -1.630247713   2.823671869   7.209073955
Zn      -0.005796021   3.761549488   7.866297372
O        0.010971356   3.771230138   9.869611927
Zn       3.141026385   0.068975484  -0.085296951
O        3.245288248   0.008779869   1.918954244
Zn       4.890743142   0.921426124   2.588903716
O        4.890743142   0.921648034   4.602875645
Zn       3.248073903   0.007171570   5.284174983
O        3.217608545   0.024760753   7.291900841
Zn       4.890743142   0.947916625   7.866297372
O        4.890743142   0.928555326   9.869611927
Zn       1.630247713   2.685720902  -0.085296951
O        1.630247713   2.806112131   1.918954244
Zn       3.243350004   3.774794739   2.588903716
O        3.243542184   3.774683784   4.602875645
Zn       1.630247713   2.809328729   5.284174983
O        1.630247713   2.774150362   7.291900841
Zn       3.266291452   3.761549488   7.866297372
O        3.249524075   3.771230138   9.869611927
END_POSITIONS
K_POINTS { gamma }
CELL_PARAMETERS (alat)
   0.990204093   0.000000000   0.000000000
  -0.495102046   0.857541899   0.000000000
   0.000000000   0.000000000   1.593439130
END_ENGINE_INPUT
END



  ------------------------------ iteration 399 ------------------------------

     tcpu = 210242.2    self-consistency for image   1
     tcpu = 210271.1    self-consistency for image   2
     tcpu = 210324.6    self-consistency for image   3
     tcpu = 210381.9    self-consistency for image   4
     tcpu = 210438.7    self-consistency for image   5
     tcpu = 210486.7    self-consistency for image   6
     tcpu = 210537.2    self-consistency for image   7
     tcpu = 210578.7    self-consistency for image   8
     tcpu = 210627.8    self-consistency for image   9
     tcpu = 210666.1    self-consistency for image  10
     tcpu = 210734.1    self-consistency for image  11

     activation energy (->) =   4.580093 eV
     activation energy (<-) =   8.037682 eV

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

         1     -34106.9092469            0.006369            F
         2     -34102.3291535            0.605640            F
         3     -34102.8895685            1.158753            F
         4     -34105.0515033            0.865640            F
         5     -34105.6100789            1.294421            F
         6     -34105.4403976            1.432055            F
         7     -34105.6758234            0.826339            F
         8     -34107.2351238            1.339071            F
         9     -34109.1414072            0.998529            F
        10     -34108.5580817            0.209370            F
        11     -34110.3668356            0.005283            F

     climbing image =  2

     path length          = 70.443 bohr
     inter-image distance =  7.044 bohr

     ------------------------------ iteration 400 ------------------------------

     tcpu = 210765.4    self-consistency for image   1
     tcpu = 210793.9    self-consistency for image   2
     tcpu = 210856.3    self-consistency for image   3
     tcpu = 210914.9    self-consistency for image   4
     tcpu = 210967.2    self-consistency for image   5
     tcpu = 211009.7    self-consistency for image   6
     tcpu = 211065.9    self-consistency for image   7
     tcpu = 211107.7    self-consistency for image   8
     tcpu = 211151.6    self-consistency for image   9
     tcpu = 211218.4    self-consistency for image  10
     tcpu = 211254.5    self-consistency for image  11

     activation energy (->) =   4.418264 eV
     activation energy (<-) =   7.875850 eV

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

         1     -34106.9092488            0.004969            F
         2     -34102.4909845            0.540194            F
         3     -34102.6931257            0.944989            F
         4     -34105.1157094            1.093132            F
         5     -34105.4771272            1.356036            F
         6     -34105.4713986            1.263916            F
         7     -34105.6439104            0.823393            F
         8     -34107.1909738            1.387148            F
         9     -34109.0480823            0.987422            F
        10     -34108.5683495            0.232949            F
        11     -34110.3668349            0.005386            F

     climbing image =  2

     path length          = 70.431 bohr
     inter-image distance =  7.043 bohr

     ---------------------------------------------------------------------------


     neb: reached the maximum number of steps
 
     NEB          :     1d    2h23m CPU        2d   10h41m WALL

 
   This run was terminated on:  19:11:38   7Nov2012            

=------------------------------------------------------------------------------=
   JOB DONE.
=------------------------------------------------------------------------------=



More information about the users mailing list