NEB calculation

Queries about input and output files, running specific calculations, etc.


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ccccc
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NEB calculation

#1 Post by ccccc » Thu Feb 25, 2010 9:10 am

I want to learn how to specify the "relaxation of atoms perpendicular to the reaction path" in NEB calculation?

Is it different from a normal relaxation process? Which parameter should i write into the INCAR file and what is its default value during NEB?
Last edited by ccccc on Thu Feb 25, 2010 9:10 am, edited 1 time in total.

alex
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NEB calculation

#2 Post by alex » Thu Feb 25, 2010 1:51 pm

What happened to reading manuals or websites first?
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ccccc
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NEB calculation

#3 Post by ccccc » Thu Feb 25, 2010 2:05 pm

I created all inter geometries between initial and final states. I prepared an INCAR file according to the manuel and put the NSW =1. because in my opininon i dont need any relaxation at this stage, because i have the stable geometry. but in a few paper, i saw some explanations about perpendicular forces during NEB. Actually, i dont understand the logic of perpendicular relaxation to the reaction path. can you tell me its meaning please?

thank you much.
Last edited by ccccc on Thu Feb 25, 2010 2:05 pm, edited 1 time in total.

boris
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NEB calculation

#4 Post by boris » Thu Feb 25, 2010 2:57 pm

Hi

In NEB calculations, you cannot allow a complete relaxation of all forces. If you do so, the transition state will likely get back to a more stable state.

This is the reason why the NEB calculation only optimizes some components of the forces.

But you don't have to care about this, you just perform your NEB calculation and it will take care of this for you.

Regards
Last edited by boris on Thu Feb 25, 2010 2:57 pm, edited 1 time in total.

ccccc
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NEB calculation

#5 Post by ccccc » Thu Feb 25, 2010 3:35 pm

Dear Boris
Thank you for your attention.

But my problem still continues. An example of a sentence from a paper "In the first levels, typically more than 100 iterations of NEB were carried out until the forces perpendicular to the reaction path were considerably small." or another says " The NEB method takes a set of images of the system between the initial and final states and optimizes them simultaneously in a subspaceperpendicular to the imaginary line connecting the images."

Here i dont understand this. if the NEB calculation does a relaxation, the geometry goes its most stable structure. so what does those sentences above tell us?
Last edited by ccccc on Thu Feb 25, 2010 3:35 pm, edited 1 time in total.

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