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

[Thomas Kühne]

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 <http://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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