[Pw_forum] zero activation energy in NEB calculations

[manchugh at iitk.ac.in]

Thanks a lot Giuseppe Mattioli
How can I be so ignorant? I did not notice the energies at all.
Now I am checking it!!
Thank you
Manjusha
IIT Kanpur
Kanpur

>
> Dear Manjusha
>
>       activation energy (->) =   0.000000 eV
>       activation energy (<-) =   0.000000 eV
>
>       image        energy (eV)        error (eV/A)        frozen
>
>           1     -64917.3691663            3.118784            T
>           2     -64919.6863336            2.357326            F
>           3     -64918.3306026            3.752568            F
>           4     -64918.3307659            3.754808            F
>           5     -64919.6865281            2.355640            F
>           6     -64917.3691661            3.119165            T
>
>       path length          =  7.684 bohr
>       inter-image distance =  1.537 bohr
>
> It seems that your first and last images are not potential energy
> minima. Try to optimize their geometry and check if, after
> optimization, they are still what you expect. Then perform the neb
> calculation.
> HTH
> Giueppe
>
> Giuseppe Mattioli
> ISM-CNR
> Italy
>
> Quoting manchugh at iitk.ac.in:
>
>> Dear all
>>
>> I am doing NEB calculation to find the MEP between two states using
>> version neb-5.0.2. First, I want to get the path trajectory using no-CI
>> and after 10-15 iterations, if the path trajectory is stabilized, I will
>> use CI. But after 2nd iteration in my no-CI calculation, I am getting
>> zero
>> activation energy. My system is Ga terminated surface of GaN(0001) and
>> one
>> N atom is diffusing from one fcc site to another for which I am
>> calculating MEP.
>> Input and output files are attached. (The output is not complete since
>> job
>> is still running). Can anyone clarify why activation energy is zero?
>>
>> Thank you for your time
>> Manjusha
>> IIT Kanpur
>> India
>
>
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-- 
Manjusha
Research Scholar
C/O Dr. Madhav Ranganathan
Department of Chemistry
Indian Institute of Technology,Kanpur
U.P., India 208016
Lab-SL302
ph:+91-512-259 6539