[CP2K-user] [CP2K:20762] Inconsistent geometry optimisations

['daniel Storm' via cp2k]

Hi Matthias,

I did have a look at the cutoff and EPS_DEFAULT at the start of my project 
but that was for a different issue. So I haven't tried running consecutive 
optimisations with these parameters but I will give that a go and get back 
to you.

Thanks for your help,

Daniel

On Tuesday, October 8, 2024 at 2:35:01 PM UTC+1 Krack Matthias wrote:

> Hi Daniel
>
>  
>
> Did you try to decrease EPS_DEFAULT and to increase the PW cutoff? These 
> input parameters mainly determine the accuracy of the atomic forces rather 
> than the convergence thresholds for the force calculation like MAX_FORCE or 
> MAX_DR which can also show convergence for poor forces.
>
>  
>
> HTH
>
>  
>
> Matthias
>
>  
>
> *From: *'daniel Storm' via cp2k <cp... at googlegroups.com>
> *Date: *Tuesday, 8 October 2024 at 14:50
> *To: *cp2k <cp... at googlegroups.com>
> *Subject: *[CP2K:20756] Inconsistent geometry optimisations
>
> Hi everyone,
>
> Just to provide some context, in our group we use CP2k to model molecular 
> reactivity in the solid state, so slightly different than “standard” solid 
> state chemistry. We run optimisations for minima and transition states 
> (TS), whose character we confirm by running phonon calculations.
>
> Now, to the issue. I am working with a crystal structure of an iridium 
> organometallic salt, [Ir(PONOP)(H)Me][BArF4], however, I am encountering 
> issues with achieving consistent optimisations. Despite starting from the 
> same experimental structure, I am getting very different SCF energies (up 
> to 3 kcal/mol) and I have observed minor differences in the resulting 
> geometries. I think that those geometries are close enough to not show that 
> big of an SCF difference, but my main worry is the fact that the starting 
> point is always the same.
>
> The convergence criteria that I am currently using is MAX_FORCE 1.0 x 10-4. 
> I have attempted to improve this by tightening the criteria (MAX_FORCE, 
> MAX_DR, RMS_DR and RMS_FORCE) to 1.0 x 10-6, but this didn’t fix the 
> issue. All the optimisations are done with the PBE-D3 functional and 
> DZVP-MOLOPT-SR-GTH basis set.
>
> So, to sum up, I run optimisations with the same starting geometry that 
> converge to different structures, and I am not sure why or which criterion 
> to use to select one structure over the other, etc. 
>
> I have worked with other organometallic salts in the past, and this is the 
> first time I find this issue. I am using CP2k version 2023.2 in the HPC 
> cluster Archer-2.
>
> Has anyone seen this before? Any advice on how to proceed?
>
> Thanks in advance,
>
> Daniel.
>
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