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

[Mostafa Abedi]

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 Tuesday, April 7, 2020 at 5:20:12 PM UTC-4, tkuehne 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 <mos... at brown.edu 
> <javascript:>>:
>
> 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
>>
>>
> -- 
> You received this message because you are subscribed to the Google Groups 
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> To view this discussion on the web visit 
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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
> td... at mail.upb.de <javascript:>
> +49/(0)5251/60-5726
>
>
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