vef.pl and nebresults.pl provide different forces for the same run - expert advice needed!

Vasp transition state theory tools

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ravindra
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Joined: Wed Aug 19, 2020 11:49 pm

vef.pl and nebresults.pl provide different forces for the same run - expert advice needed!

Post by ravindra »

Hi folks,

I am in need of some expert help. This question may be trivial to some of you but your input will be quite helpful for my manuscript.
NEB calculation has converged but if I go into individual image directory and run vef.pl or vef.py, I get a certain Force vs Ionic steps graph....

BUT, if I run nebresults.pl script in the parent directory, the forces are different and much smaller.
I don't know which graph to trust. I have attached both graphs here and your advice would be very much appreciated.
Attachments
nebresults.pl script
nebresults.pl script
Image2_nebresults_script.png (50.3 KiB) Viewed 1260 times
vef.pl script run within the image directory
vef.pl script run within the image directory
Image2_vefpl_script.png (48.22 KiB) Viewed 1260 times
graeme
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Re: vef.pl and nebresults.pl provide different forces for the same run - expert advice needed!

Post by graeme »

If you attach a tar.gz file of the simulation I can help with this question. Most likely there is a simple explanation - the NEB forces are composed of only the real forces perpendicular to the path plus a spring force to keep the images equally spaced. For convergence, you should look at the NEB forces.
ravindra
Posts: 3
Joined: Wed Aug 19, 2020 11:49 pm

Re: vef.pl and nebresults.pl provide different forces for the same run - expert advice needed!

Post by ravindra »

Many thanks for your prompt response!
I have attached the entire simulation with OUTCARs in the respective image folders. [File name = neb.zip, around 396 MB]
Your explanation will help me understand the conceptual framework better. Very grateful for your help.
Attachments
neb.zip
Entire NEB simulation file
(396.5 MiB) Downloaded 157 times
ravindra
Posts: 3
Joined: Wed Aug 19, 2020 11:49 pm

Re: vef.pl and nebresults.pl provide different forces for the same run - expert advice needed!

Post by ravindra »

I have attached the results in the post above.
Many thanks for your Prof. Henkelman.

graeme wrote:
> If you attach a tar.gz file of the simulation I can help with this
> question. Most likely there is a simple explanation - the NEB forces are
> composed of only the real forces perpendicular to the path plus a spring
> force to keep the images equally spaced. For convergence, you should look
> at the NEB forces.
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