[CP2K-user] [CP2K:14857] Re: Severe deformation of structure during geometry optimization

[Lenard Carroll]

I will look into those things, maybe I will get lucky.

In terms of dipole correction, it's been a nightmare for me to work. I have
posted a few questions in this forum about it.

On Tue, Mar 2, 2021 at 6:37 PM Matt W <mattwa... at gmail.com> wrote:

> I normally use WAVELET poisson solver - then you need Y as the
> non-periodic direction (so PERIODIC XZ), the system must be in the centre
> of the cell and you need ~5 A vacuum each side to get converged results.
>
> The ANALYTIC psolver is also usable for 2D poisson, but it requires a much
> bigger cell to converge (~2x), to my knowledge.
>
> Do check that you are converged with cell size if you go these routes.
> There is also a dipole correction method available somewhere (I've not
> used).
>
> Matt
>
> On Tuesday, March 2, 2021 at 4:04:03 PM UTC Lucas Lodeiro wrote:
>
>> 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 (<len... 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 <el... 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 (<len... 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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