[CP2K-user] [CP2K:13081] large temperature fluctuation in NVT AIMD

[Abedi, Mostafa]

You are right, I just changed the unit cell in the input file to the one
that fits the structure. Is there any program/visualizer for preparing the
initial state that takes the presence of periodic boundary conditions into
account?

Mostafa

On Tue, Apr 7, 2020 at 5:20 PM Thomas Kühne <tku... at gmail.com> wrote:

> Have you also adapted the coordinates, or simply modified the cell
> geometry?
> If not you may first try to carefully prepare your initial state taken the
> presence
> of periodic boundary conditions into account ...
>
> Cheers,
> Thomas
>
> Am 07.04.2020 um 23:08 schrieb Mostafa Abedi <mostaf... at brown.edu>:
>
> Dear Thomas,
>
> Many thanks for your help. I've changed the input file according to your
> suggestion. However, the temperature fluctuation is getting larger. I
> attached the corresponding files. I really appropriate if you could have
> another look into this. Thanks.
>
> Best,
>
> Mostafa
>
>
>
>
>
> On Tuesday, April 7, 2020 at 4:14:44 PM UTC-4, tkuehne wrote:
>>
>> Dear Mostafa,
>>
>> you are relying on the default values for the thermostat. For such a
>> small system (the fluctuations scale with the sqrt
>> of the number of particles), a strong coupling is necessary. Try for
>> instance REGION MASSIVE, TYPE CSVR and
>> TIMECON 50. More importantly, however, the dimension of your cell is too
>> large resulting in a way too low density.
>>
>> Cheers,
>> Thomas
>>
>> Am 07.04.2020 um 21:51 schrieb Mostafa Abedi <abe... at gmail.com>:
>>
>> Hi Everybody,
>>
>> I am trying to do NVT AIMD simulations for a system consisting of 16 H2O
>> molecule. Strangely, the temperature fluctuation is very large (see
>> attached "WATER-1.ener" file). I know a little bit temperature fluctuation
>> is acceptable, but mine is really large. This is the first time I am trying
>> CP2K for doing AIMD and not familiar with structure of the input file.
>> Maybe something is wrong or missing in the input file (see attached
>> "water.inp" file). I should say I've already done this calculation with
>> ORCA for non-periodic water system. Now, I want to see the effect of
>> periodicity with cp2k. Any help would greatly appropriated. Many thanks.
>>
>> Best,
>> Mostafa
>>
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>> .
>> <WATER-1.ener><water.inp><water.xyz>
>>
>>
>>
>>
>> ==============================
>> Thomas D. Kühne
>> Dynamics of Condensed Matter
>> Chair of Theoretical Chemistry
>> University of Paderborn
>> Warburger Str. 100
>> D-33098 Paderborn
>> Germany
>> td... at mail.upb.de
>> +49/(0)5251/60-5726
>>
>>
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> .
> <water.inp><WATER-1.ener>
>
>
>
>
> ==============================
> Thomas D. Kühne
> Dynamics of Condensed Matter
> Chair of Theoretical Chemistry
> University of Paderborn
> Warburger Str. 100
> D-33098 Paderborn
> Germany
> tdku... at mail.upb.de
> +49/(0)5251/60-5726
>
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>
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