[Pw_forum] NEB calculation

[Prasenjit Ghosh]

Dear Savita,

In addition to what Layla has said, I think 40 bohrs vacuum is too
large.....until & unless you have evidence that you really need 40 bohrs, I
would suggest you to reduce the vacuum to about 25 bohr.

Also try to post your input file......without that it is difficult to
provide any suggestions.

Prasenjit.

On 18 April 2011 15:09, Layla Martin-Samos <lmartinsamos at gmail.com> wrote:

> Dear Savita, when there is no idea about the atomic configuration of
> intermediate minima, it is usually more convenient to divide your problem in
> two steps or more, because NEB converge better if the MEP contains only one
> main single barrier, for instance:
>
> 1) formation of CO2 (maybe this should be divided in more steps)
> 2) CO2 desorption
>
> bests regards
>
> Layla
>
> 2011/4/18 <psavita at crlindia.com>
>
>> Hello,
>>
>> I am performing NEB calculation wherein first image has CO and O adsorbed
>> at the atop and fcc sites respectively
>> on 3 layer Pt(111). The last image is a linear CO2 about 10 bohr away from
>> the slab, a vacuum layer of 40 bohr is used
>> above the slab. This is turning into quite a compute intensive task, there
>> is no sign of convergence even after 20
>> NEB iterations, the residual forces are still quite large. I have a total
>> of 5 images and there is no CI.
>>
>> Is this no. of images proper?
>> Which other factors do I need to control better to get meaningful results?
>>
>> Thank you in advance,
>>
>> Sincerely,
>>
>> Savita Pundlik
>> Computational Materials Applied Research Group
>> Computational Research Laboratories Ltd.,
>> Taco House, Damle Path, Off Law College Road
>> Pune - 411004, India.
>>
>>
>>
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-- 
PRASENJIT GHOSH,
Assistant Professor,
IISER Pune,
First floor, Central Tower, Sai Trinity Building
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Pune, Maharashtra 411021, India

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