[CP2K-user] [CP2K:21520] Re: Implicit solvent DFT calculation - charge runaway using SCCS

[Marcella Iannuzzi]

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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