Hi,
The official documentation states on the page about SPRING:
Do not use too large values, because this can slow down convergence. The default value usually works quite reliably.
How large is too large? Is -7.5 a too big?
NEB SPRING, how much is too much?
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filipejunqueira
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merzuk.kaltak
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Re: NEB SPRING, how much is too much?
Hello,
the short answer is: "It depends". Your proposal does not seem completely unreasonable.
This is especially true, if you have a "floppy" band for the default value of -5.
By floppy band, I mean one or more local minima in energy between initial and final state appear.
Here a bigger SPRING value can definitely help to obtain a smooth energy barrier.
Bear in mind though, a too big SPRING value might force your system into wrong transition states.
Alternatively, if you know the image with the highest energy in your NEB the hill climbing method is a good alternative.
Here you would pick this image and relax it using steepest ascent and interpolate the initial and final state through this hill top image.
the short answer is: "It depends". Your proposal does not seem completely unreasonable.
This is especially true, if you have a "floppy" band for the default value of -5.
By floppy band, I mean one or more local minima in energy between initial and final state appear.
Here a bigger SPRING value can definitely help to obtain a smooth energy barrier.
Bear in mind though, a too big SPRING value might force your system into wrong transition states.
Alternatively, if you know the image with the highest energy in your NEB the hill climbing method is a good alternative.
Here you would pick this image and relax it using steepest ascent and interpolate the initial and final state through this hill top image.