[CP2K-user] [CP2K:17739] Need help to increase compute speed

[Dev Rana]

Hi lucas,

Thank you for this. This definitely speeds things up.

I feel like I'm missing something in your explanation. You say that 62 Cu + 
1 C = 686 electrons total. Cu has 29 electrons * 62 Cu atoms = 1798. 1 C = 
6 electrons. So This should be 1802. With roughly half occupied = 901 and 
20% of that is still roughly 200. I agree that 200 is too much - but how 
you obtained 70 is a bit confusing to me.

Could you explain how you reached your conclusion?

Thanks!

On Monday, July 25, 2022 at 7:37:56 PM UTC-4 Lucas Lodeiro wrote:

> Hello Rev Rana,
>
> From your input, I see 2 thing that could improve your calculation. First 
> you use a CUTOFF of 600 and a REL_CUTOFF of 250. This is a little weird to 
> me... usually REL_CUTOFF is around 60.... using higher values will slow 
> down your calculation without a real improvement over the calculation 
> results. Do you do a convergence study of these parameters?
> Second, you are adding 200 MOs to your calculation... Obviously you need 
> some virtual orbitals to use the smearing, but the greater the number of 
> these, the slower the calculation is. So, 200 is in my opinion too much. 
> Your system has 62 Cu and 1 C atoms, with 686 electrons in total, this is 
> 343 occupied orbitals (only as a mental exercise). Usually adding 20% more 
> orbitals is enough. so adding just 70 orbitals would be sufficient, and 
> make your calculations faster.
>
> Regards - Lucas
>
>
> El lun, 25 jul 2022 a las 20:01, Dev Rana (<dev.... at gmail.com>) escribió:
>
>> Hello,
>>
>> I'm having some trouble conducting an MD simulation. Each SCF iteration 
>> takes about 100-200 seconds taking about 15-30 iterations per MD step. 
>> Could someone experienced take a look at my input file to see if there is 
>> any input which could be added/removed to increase speed? I've attached my 
>> restart file containing all information. 
>>
>> I'm using a computing node with openMPI OMP threads set to 2, and 64 
>> cores on a single exclusive node (no multi-node delays). 
>>
>> Best Regards,
>> Devyesh Rana
>>
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