Vacancy migration frequency

Vasp transition state theory tools

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Chaure
Posts: 18
Joined: Tue Dec 03, 2019 11:16 pm

Vacancy migration frequency

Post by Chaure »

Dear users,
If I calculate energy barrier for vacancy migration, How Can one calculate vacancy migration frequency ?
Sincerely

graeme
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Re: Vacancy migration frequency

Post by graeme »

Within the harmonic approximation, you need to calculate the normal mode frequencies at the reactant and saddle point. Then the attempt frequency for hopping is given by: v = Prod v_rs / Prod v_ts , where Prod is the product of all the positive frequencies v = w/2pi, rs is the reactant state and ts is the saddle point.

Chaure
Posts: 18
Joined: Tue Dec 03, 2019 11:16 pm

Re: Vacancy migration frequency

Post by Chaure »

Dear Professor,
Is there any link to calculate normal mode frequency at reactant and saddle point?
Sincerely


Chaure
Posts: 18
Joined: Tue Dec 03, 2019 11:16 pm

Re: Vacancy migration frequency

Post by Chaure »

Dear Professor,
Can we use the INCAR tags to run vibrational frequency like IBRION = 5 or 6 in the same NEB run. Also Do we need to set selective dynamics like calculating mode in one direction like z.
Sincerely

graeme
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Posts: 1915
Joined: Tue Apr 26, 2005 4:25 am
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Re: Vacancy migration frequency

Post by graeme »

You are able to freeze atoms using the selective dynamics tags. Keep those same setting for the dynamical matrix calculation.

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