Inquiry Regarding High Energy Barrier in CI-NEB Calculation

[emmanuel_adejumo]

Dear VASP Support Team,

I am performing CI-NEB calculations to investigate Li diffusion in amorphous Mo₃S₁₃. I inserted lithium into the system and created initial and final structures, both of which converged to the required accuracy during optimization before the NEB calculation. However, my NEB results indicate a significantly high diffusion barrier, which appears questionable despite the absence of experimental data for direct comparison. Given the results, I suspect that something may be incorrect in my setup or calculation procedure.

Here are the key energy values from my NEB calculation:

`0 0.009413 -1482.799300 0.000000 1 0.325824 -1008.260400 474.538900 2 0.372460 -1245.674300 237.125000 3 0.357279 -1394.222900 88.576400 4 0.261281 -1406.740700 76.058600 5 0.008624 -1482.735000 0.064300`
Given these values, I am concerned that the computed barrier may not be physically accurate. I would appreciate any insights or possible explanations regarding this issue.

Please find attached my input files for your reference.

Thank you for your assistance.

Best regards,
Emmanuel

[ferenc_karsai]

I've moved this topic to "from users to users".

[ferenc_karsai]

I have no experience with NEB (and the most of us at VASP also have no experience), so I can only look at your input files and see if I see something there.

The file looks reasonable. Also the plotted reaction barrier you attached looks smooth.
How was your electronic relaxation, did it always converge? You used ALGO=VeryFast and Prec=Low, maybe you could try ALGO=normal and PREC=normal and see how the results change.

Otherwise I hope maybe someone in the forum here with NEB experience can give you an advice.

[emmanuel_adejumo]

Thank you for taking a look at my input files and reaction barrier plot. My electronic relaxation generally converged, but I will check the convergence behavior more carefully. I'll also try running with ALGO=Normal and PREC=Normal to see if that affects the results.

I appreciate your feedback, and I'll wait to see if someone with more NEB experience can provide further insights. Let me know if you notice anything else that might be worth adjusting!