[Pw_forum] NEB first_last_opt

[Aleksandra Oranskaia]

Hello dear QE users,

I have a question regarding pre-optimization of starting and ending points of NEB.

Dealing with multi-scale simulation of a vacancy migration in a huge supercell (say, 350-400 atoms), should one make a pre-optimization of starting and ending points of a path?

I tried both ways and came to the conclusion that pre-optimization pushes the system away from the minimum energy path (leading to the increased barriers), because pre-optimization implies too deep restructuring towards deeper minimums rather than the local minimums closest to the minimum energy pathway.
In my opinion it is more physical if a migration corresponds to a minimum energy pathway AND minimum restructuring.

If you would simulate vacancy migration in a huge supercell with NEB optimization, would you optimize starting and ending points? Why?


Thanks in advance and hope to hear your opinions and reasonings,

Regards,
Alex.
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