[Pw_forum] Difficult to reach final path in NEB calculation

[Jibiao Li]

Dear QE community,


I am using neb.x to calculate minimum energy path for CO reaction on Fe(100), but found the run is difficult to reach the final path. The errors (shown below) are still large even after 32 iterations. Is it a problem regarding parameters setting in the input file? I need your help to resolve this issue and get the final path done.


Best


Jibiao Li


Yangtze Normal Univeristy, China 






     activation energy (->) =   5.592640 eV
     activation energy (<-) =   4.183596 eV


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


         1    -129447.5858384            0.019300            T
         2    -129447.0615057            7.395136            F
         3    -129445.5166741           11.112200            F
         4    -129444.1612192            7.928737            F
         5    -129441.9931983            2.747658            F
         6    -129443.6922298            9.825364            F
         7    -129446.1767943            0.022586            T


     climbing image =  5


     path length          = 11.835 bohr
     inter-image distance =  1.972 bohr


     ------------------------------ iteration  33 ------------------------------




BEGIN
BEGIN_PATH_INPUT
&PATH
  restart_mode      = 'from_scratch'
  string_method     = 'neb',
  nstep_path        = 50,
  ds                = 2.D0,
  opt_scheme        = "broyden",
  num_of_images     = 7,
  k_max             = 0.3D0,
  k_min             = 0.2D0,
  CI_scheme         = "auto",
  path_thr          = 0.1D0,
/
END_PATH_INPUT
BEGIN_ENGINE_INPUT
&CONTROL
  prefix         = "tri"
  outdir         = "./",
  pseudo_dir     = "/home/bmllzr/codes/pseudo/",
/
&SYSTEM
                       ibrav = 6,
                   celldm(1) = 16.270548418,
                   celldm(3) = 2.32,
                         nat = 54,
                        ntyp = 3,
                     ecutwfc = 29 ,
                     ecutrho = 180 ,
                 occupations = 'smearing' ,
                     degauss = 0.05D0 ,
                    smearing = 'methfessel-paxton' ,
                       nspin = 2 ,
   starting_magnetization(1) = -0.1,
   starting_magnetization(2) = -0.1,
   starting_magnetization(3) = 2.9,
            exxdiv_treatment = 'gygi-baldereschi' ,
/
&ELECTRONS
                 mixing_beta = 0.2D0 ,
             diagonalization = 'david' ,
/
&IONS
/
ATOMIC_SPECIES
    O   15.999  O.pbe-van_ak.UPF 
    C   12.001  C.pbe-van_ak.UPF 
   Fe   55.850 Fe.pbe-sp-van_ak.UPF 
BEGIN_POSITIONS
FIRST_IMAGE
ATOMIC_POSITIONS angstrom 
...
LAST_IMAGE
ATOMIC_POSITIONS angstrom 
...
END_POSITIONS
K_POINTS automatic 
  3 3 1   0 0 0 
END_ENGINE_INPUT
END
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20171006/968d2ea2/attachment.html>