[CP2K-user] [CP2K:21534] Re: Implicit solvent DFT calculation - charge runaway using SCCS

[Andreas Döll]

Hello Marcella,

these covalent organic framework structures I want to study in the end via 
MD in lammps are porous structures (need partial RESP charges as input from 
DFT), so although solvent between layers is probably not possible,
the solvent can be in the pore of the structure. I want to study if the 
effect of the solvent affects the charge distribution is a major way, that 
is why I was interested in implicit solvent in the first place.
I have included kpoints Monkhorst 2 2 10 and removed SCCS for now, as well 
as OT as it clashes with Kpoints.

Now I can report back to You:
I have problems getting the the geometric optimization to work out, even 
when removing SCCS! I head that implicit solvent helps out with 
convergence, that is why I thought maybe SCCS will help out to solve 2 
problems at the same time. Do You have any advice how to properly converge 
the structure? I did a preoptimization for the initial structure with a 
generic forcefield in avogadro, but still my SCF does not converge, wether 
I try with OT or kpoints or mixing.. I am a bit lost on how to proceed.
Any help is welcome.

Sincerely, 
Andreas Doell

Marcella Iannuzzi schrieb am Freitag, 6. Juni 2025 um 10:24:43 UTC+2:

> Hi Andreas, 
>
> I see that the cell  is very small along z. Where is supposed to be the 
> solvent?
> Anyway, such small cells are in general problematic without kponts.
> Have you tried without SCCS?
> Regards
> Marcella
>
> On Wednesday, June 4, 2025 at 6:15:47 PM UTC+2 andreas... at gmail.com wrote:
>
>> 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
>>>>>
>>>>>
>>>>>

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/cp2k/bc621033-d09f-432c-8e1b-9bf90a5b1a73n%40googlegroups.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250612/8c77c1b1/attachment-0001.htm>