NEB Calculation in Fe

Dear lammps users

I want to calculate the diffusion energy barrier in Fe for vacancy diffusion. For that I have created a vacancy and then marked an atom nearest to the vacancy.The marked atom then allowed to go to the position of the vacancy. But I found that the barrier energy is 0.00028 eV but in literature it is reported around 0.628 eV_(Nuclear Instruments and Methods in Physics Research B 307 (2013) 37–39)_.I have used FS potential. I have also used different type potential but the results are nearly same.I can’t understand where is my mistake.I am attaching the input files and output file.I would be thankful to you if you go through the input file and tell me the mistakes.

Thanks

Regards

Ali

nebproblem.zip (216 KB)

Hi,
The value is certainly around 0.63 eV, for most potentials.
I'm not actually fully understand your script. But you just let so few
atoms to relax, and others been setforce 0. I'm not sure whether if it
would also affect the energy calculation, but just want tell you, it
seems necessary to let more atoms to relax, say "nebatoms" group
should be larger. And the barrier calculation requires a very small
energy tolerance, I set 0 to get the desired value, even 1e-12 is not
good enough.

2014/1/10, Kawsar Ali <[email protected]>: