[CP2K-user] MD calculation of NPT_F ensemble including baro- and thermostats at various T

[Lukas C]

Hi Marcella! Hi everyone!

I tried to run the annealing as suggested. So I turned off the thermostats 
and choose an NPE_F ensemble. The temperature is changed very gently: 
starting from 2K, with a rescaling factor for the velocities of 1.01, it 
should reach 3.127K after 50 steps. Unfortunately, I get unexplained MPI 
errors at the end of the first SCF step which apart from that converges 
nicely and does not show any signs of malfunction. I do get a WARNING 
before the SCF cycle starts, namely when calculating the PDOS at iteration 
step 0. All the input and output files (except for the .wfn file which is 
too large) are attached. I tried running it with different preconditioners 
but this did not change anything. I even ran the simulation on another 
cluster where it got stuck at the same point.
Any thoughts on this? Thank you!

Kind regards,
Lukas

Lukas C schrieb am Dienstag, 17. November 2020 um 10:08:26 UTC+1:

> Dear Marcella!
>
> Thank you so much for your help! I understand a lot more now. I will try 
> to incorporate your advices and keep you updated about any progress.
>
> Best regards,
> Lukas
>
> Marcella Iannuzzi schrieb am Montag, 16. November 2020 um 16:27:03 UTC+1:
>
>>
>> Dear Lukas, 
>>
>> It is recommendable to monitor the behaviour of the system at conditions 
>> closer to equilibrium. 
>> Jumping from 0K to 3000K seems quite ambitious. 
>>
>> The conserved quantity has to be conserved also with the NPT ensemble, 
>> where it is not simply the sum of pot. and kin. energy, but it includes all 
>> the due terms of the extended ensemble. If it is not conserved there is a 
>> problem.  
>> I would be conservative with the choice of the thermostat, Nose-Hoover 
>> and CSVR are for sure reliable. 
>> Adding a thermostat to the barostat helps in controlling the cell 
>> fluctuations, that indeed are quite wild according to the posted example. 
>> Anyway, monitoring the stress is also useful to check on the sanity of 
>> the system. 
>>
>> For the annealing, I would rather suggest a step-wise procedure, i.e. 
>> running a series of run at increasing temperature  (\Delta T ~ 200 K ), 
>> starting always from the previous one. 
>>
>> Kind regards
>> Marcella
>>
>>
>>
>>
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