[Pw_forum] transition state using NEB
Ravi Kiran
ravikirans.87 at gmail.com
Sat Jan 31 00:13:18 CET 2015
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
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