[CP2K-user] [CP2K:18140] Re: Temperature drift in polaron study

Vinayak Vinayak vinayakv at seas.upenn.edu
Fri Dec 2 18:14:31 UTC 2022


Hi Marcella,

Thanks a lot for your advice! I have been trying to follow it but still 
facing some issues.
1. The simulation has run for 500 fs and seems to be settling around 150K 
rather than 300K (plot attached). I dont see how that may increase later.
2. For some reason it is taking us a lot of time to run even 500fs of 
calculations. It has taken a week to run just 500fs. 
I am using 6 nodes, with 32 cores on each using mpirun. The jobs script is 
attached as well. Is this the speed one should expect or is there a faster 
way to proceed?
We have 192 atoms in the system, so we have tried to optimize for that as 
well. 

It would be extremely helpful if you could help us with the above. 

Thanks a lot,
Vinayak

On Monday, November 14, 2022 at 4:38:09 AM UTC-5 Marcella Iannuzzi wrote:

> Dear Vinayak
>
> Starting from an optimised geometry it is expected that the just 
> initialised finite temperature decreases. 
> Even by setting a thermostat (NVT), it takes quite some time  (some ps) 
> before the thermostat succeeds in equilibrating the system to the desired 
> temperature. 
>
> Regards
> Marcella
>
>
> On Friday, November 11, 2022 at 6:10:44 PM UTC+1 vina... at seas.upenn.edu 
> wrote:
>
>> Hi All,
>>
>> Thanks for creating this wonderful forum for cp2k. 
>> I am new to AIMD simulations but have been doing MD and DFT separately 
>> for some time. Currently I am trying to do a polaron evolution study in a 
>> pervoskite at a finite temperature. The 0K results are great and as 
>> expected but with MD at 300K and Nose thermostat I see a large temperature 
>> drift in the first few fs. I have performed geometrical optimisation on the 
>> supercell. Please find all the files which I use attached. You can also 
>> find the .ener file where you can see the quick drift. 
>>
>> Any help would be extremely appreciated.
>>
>> Thanks,
>> Vinayak
>>
>

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