[CP2K-user] [CP2K:14840] convergence problem of Ions in implicit water (SCCS)

[li bingxin]

Hi Marcella,

Thanks a lot for your suggestions.  I will try to use a larger cutoff value for the auxiliary plane waves and a smaller mixing alpha.



Best,
Bingxin 

> On 27 Feb 2021, at 13:12, Marcella Iannuzzi <marci... at gmail.com> wrote:
> 
> 
> Hi ...
> 
> I don't know the basis set that you are using for Mg, however the PW cutoff looks far too low and only 2 valence electron for Mg might be not optimal.
> I doubt that the smearing would be useful for such a system, anyway it is in general applied with mixing in the reciprocal space.
> Alpha 0.1 is not very small, you can easily need much smaller value.
> 
> Regards
> Marcella
> 
> 
> On Saturday, February 27, 2021 at 1:22:23 PM UTC+1 bin... at gmail.com <http://gmail.com/> wrote:
> Dear CP2K users,
> 
> I am trying to relax the Mg2+ solvated ions in the implicit water using the self-consistent continuum solvation (SCCS) model  implemented in the CP2K code. I have tested the parameters for water molecules inside the implicit water according to Oliviero's paper: https://aip.scitation.org/doi/10.1063/1.3676407 <https://aip.scitation.org/doi/10.1063/1.3676407>, and found a slightly more negative solvation energy (-7.77 eV) comparing to the experiment data (-6.3 eV). I assume this error can be accepted and use the aforementioned parameters for the relaxation of ions in implicit water.
> 
> However, when I try to calculate the solvated Mg2+/Mg + 6H2O clusters (anions and neutral cluster), I found the SCF can hardly get converged in this case. I tried Broyden mixing method and direct linear mixing method with small mixing alpha (0.1). But this can not make the calculation get converged. I was wondering how can I get the SCF converged (for instance, tuning the values for rho_max/min in the SCCS model)?
> 
> I have attached the input file and could anyone have any experience or ideas on this issue help me?
> 
> I am looking forward to your reply.
> 
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