[CP2K-user] [CP2K:14854] Re: Severe deformation of structure during geometry optimization

[Lucas Lodeiro]

Yes, and in &CELL too, to avoid interaction between slab replicas and their
electrostatic fields.

El mar, 2 mar 2021 a las 12:07, Lenard Carroll (<lenardc... at gmail.com>)
escribió:

> Just to be 100% clear, are you saying that for the &POISSON section which
> deals with the electrostatic potential, that I select PERIODIC XY?
>
> On Tue, Mar 2, 2021 at 4:55 PM Lucas Lodeiro <eluni... at gmail.com>
> wrote:
>
>> Just a comment, see your electrostatic potential profile. You are using a
>> periodical slab picture, then when you add a polar molecule, there is not a
>> flat potential into the vacuum, in that case, disable the periodicity in
>> this direction or add an electrostatic field to correct it.
>> Also, to check the convergence of your quantities with respect to your
>> model, you could explore bigger slabs than 6 layers.
>>
>> Regards - Lucas Lodeiro
>>
>> El mar, 2 mar 2021 a las 6:37, ASSIDUO Network (<
>> lenardc... at gmail.com>) escribió:
>>
>>> Thank you for the quick response.
>>>
>>> I understand what you are saying and it makes total sense to me. Thank
>>> you for clarifying.
>>>
>>> The 3x3x1 was just to test how my final adsorption energy changes when I
>>> change various settings, including alpha, beta, kpoints and cutoff. I got
>>> similar results to the the 5x5x1 case, however the 5x5x1 result was more
>>> accurate compared to the ltierature.
>>>
>>> On Tuesday, March 2, 2021 at 11:33:40 AM UTC+2 fa... at gmail.com wrote:
>>>
>>>> Dear Lenard,
>>>>
>>>> Yes, you have correctly answered your question. For metals you need a
>>>> quite good sampling of the brillouin zone. Therefore a gamma-point
>>>> calculation of a 5x5 angstrom unit cell is expected to yield unreasonable
>>>> results.
>>>> The fact that you managed to get a good structure with a cutoff of 300
>>>> is probably due to a coincidental error cancelling. But as soon as you
>>>> alter the configuration by adding a CO the error cancelling does not work
>>>> anymore and the structure becomes unreasonable again.
>>>>
>>>> You should make sure that your quantity of interest is converged w.r.t
>>>> the size of the k-point grid. 3x3x1still seems small to me, but maybe its
>>>> already enough for you.
>>>>
>>>> Cheers,
>>>> Fabian
>>>> On Tuesday, 2 March 2021 at 06:42:45 UTC+1 ASSIDUO Network wrote:
>>>>
>>>>> Hi there everyone, I am currently trying to geometry optimize a stack
>>>>> of Au (111) 2x2 surfaces, specifically by fixing the bottom 3 surfaces and
>>>>> relaxing the top 3.
>>>>>
>>>>> Unfortunately, the top surfaces completely mess up and the final
>>>>> structure looks bad. When I turn KPOINTS on  (3x3x1 or 5x5x1), it no longer
>>>>> happens.
>>>>> Finally, when I lower the cutoff to 300, but I leave KPOINTS off, I
>>>>> get a good optimized geometry, but when I try to perform a CO adsorption
>>>>> with that optimized structure, it severely deforms as well.
>>>>>
>>>>> Does anyone have a solution to my problem, particularly one that
>>>>> doesn't change the ELECTRONIC_TEMPERATURE, KPOINTS or CUTOFF. Is it the
>>>>> need for KPOINTS in a small structure like this that messes up the results?
>>>>>
>>>>> I have attached all my relevant files.
>>>>>
>>>>> Kind regards,
>>>>> Lenard
>>>>>
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