[Pw_forum] transition state using NEB

[Ravi Kiran]

Hi,

I am using neb to calculate activation energy of hydrogen in unit cell of
nickel. I have placed hydrogen in octahedral position and I am moving it to
another octahedral position as shown below. My question is whether neb can
calculates transition state which is tetrahedral site?. I have used a
path_thr of 0.01eV with 7 images. I have calculated the activation energy
which I am getting is 1.05 eV as shown in output, whereas the experiments
indicate 0.42.

*input *

FIRST_IMAGE
ATOMIC_POSITIONS crystal
    Ni 0 0 0
    Ni 0 0.5 0.5
    Ni 0.5 0 0.5
    Ni 0.5 0.5 0
    H  0.5 0.5 0.5
LAST_IMAGE
ATOMIC_POSITIONS crystal
    Ni 0 0 0
    Ni 0 0.5 0.5
    Ni 0.5 0 0.5
    Ni 0.5 0.5 0
    H  0.0 0.5 0.0
END_POSITIONS
*output*
 ------------------------------ iteration  56 ------------------------------

     tcpu =   6675.4    self-consistency for image   1
     tcpu =   6683.4    self-consistency for image   2
     tcpu =   6764.1    self-consistency for image   3
     tcpu =   6846.9    self-consistency for image   4
     tcpu =   6948.8    self-consistency for image   5
     tcpu =   7031.7    self-consistency for image   6
     tcpu =   7113.1    self-consistency for image   7

     activation energy (->) =   1.024248 eV
     activation energy (<-) =   1.024248 eV

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

         1      -4690.3920838            0.000000            F
         2      -4690.3237895            0.006072            F
         3      -4689.7348781            0.005158            F
         4      -4689.3678358            0.006904            F
         5      -4689.7349752            0.004005            F
         6      -4690.3237535            0.006484            F
         7      -4690.3920838            0.000000            F

     path length          =  5.711 bohr
     inter-image distance =  0.952 bohr

-- 
Thanks
Ravi
Research assistant, univ of saskatchewan canada
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20150130/752856fe/attachment.html>