[CP2K-user] [CP2K:21523] Re: Implicit solvent DFT calculation - charge runaway using SCCS

[Andreas Döll]

Hello,thank you for your very fast response. I immediately reran my 
simulations!
You are right. My cutoff was quite low, because I played around with the 
parameters when debugging. Same holds true for OT. I reran my calculations 
with
- cutoff 400 Ry
-No OT to get mixing, with Max_scf=500 still and outer_scf=50, 
eps_outer=1.0E-5, eps_eigval 1.E-5Are there any other settings which are 
not too system specific which need to be adjusted, maybe is the convergence 
criterion too stringent? I am also currently struggling to converge 
another, larger system (2 layers of the COF structure attached in my first 
post, 264 atoms in total) where I have done pre-geometric optimization with 
known forcefields from MD simulations to obtain a decent initial structure.

I attached the updated files and still obtain the problem mentioned above, 
my charge runs away (I had to restart my simulation, because I did not 
achieve convergence but the charge runaway happens way before that)

I hope for any discussion on this matter. 
Thank you very much in advance.

Sincerely, 
Andreas Doell

Marcella Iannuzzi schrieb am Montag, 2. Juni 2025 um 15:08:20 UTC+2:

> Hello Andreas, 
>
> Are you sure that the problem is SCCS? 
> I ask because the DFT settings seem not to be optimal.
> In particular, the PW cutoff is very low, which could explain the 
> incorrect calculation of the electron density and as a consequence of the 
> total charge.
>
> As side comments, the mixing of the density  is not applied when OT is 
> active.
>  With OT, it helps running fewer iterations in the inner loop, such that 
> the preconditioner is updated.
>
> Regards
> Marcella
>
>
>
> On Monday, June 2, 2025 at 2:00:46 PM UTC+2 andreas... at gmail.com wrote:
>
>> My original message was too large, which is why I attach the output in a 
>> seperate file. Due to its size it seems I have to cut it into pieces, so I 
>> present the first and last slice of the output where you can observe the 
>> charge going from 0.000002 to 73, as well as the "Cholesky decomposition 
>> failed. Matrix ill conditioned ?" after which the run fails.
>>
>>
>> Thanks You all in advance!
>>
>> Andreas Döll schrieb am Montag, 2. Juni 2025 um 13:53:44 UTC+2:
>>
>>> Hello cp2k community, 
>>>
>>> I want to calculate the RESP charges of a structure respecting periodic 
>>> boundaries in a solvent of epsilon=8. For that I want to do a geometric 
>>> optimization using the implicit solvent model. However, after some outer 
>>> SCF iterations I get the following:
>>>
>>> *** WARNING in qs_sccs.F:458 :: The system (solute) has a non-negligible 
>>> ***
>>>  *** charge of +.000002. It is recommended to use non-periodic boundary 
>>>   ***
>>>  *** conditions (PERIODIC none) combined with an appropriate Poisson     
>>>  ***
>>>  *** solver (POISSON_SOLVER MT or analytic)
>>>  
>>> This charge deviation propagates until the end where I have a charge of 
>>> 73! 
>>> I attached input and output file. I do not understand why suddenly I 
>>> have a leftover charge, which then goes wild. Is it not possible to use 
>>> SCCS in periodic systems?
>>>
>>> Cheers, 
>>> Andreas
>>>
>>>
>>>

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