[CP2K-user] [CP2K:18255] Re: TS Dimer method gives unphysical results

[DMT]

and files from the second reaction

On Monday, December 26, 2022 at 1:14:34 AM UTC+2 DMT wrote:

> Hello,
>
> I tried to use the Dimer method of optimizing TS and I get unphysical 
> results.
>
> I used this google group to find different input files and read about the 
> struggles to overcome and used the provided input settings of successful 
> runs.
>
> In both cases (files attached include input, required .xyz and output .xyz 
> from the optimization) Dimer drives the structures into having impossibly 
> short bonds, until the SCF does not even want to converge (and it would be 
> obviously impossible). It literally tries to merge some atoms in both 
> cases. I use the &DIMER_VECTOR to input the XYZ displacements from a 
> VIBRATIONAL_ANALYSIS job for the Reaction Coordinate that I am interested 
> in, using the guessed near-TS geometries. Without the DIMER_VECTOR the 
> method always chooses a wrong Reaction path. In both cases the TS geometry 
> I start with is very simple to provide, in fact I have found both TS with 
> other software, it is just very important for me to try simple systems in 
> cp2k before I move to actual research.
>
> One of the reactions is substitution in which the N LP from NH3 attacks 
> the C of CH3Cl and pushes the Cl away to form a quaternary ammonium cation 
> with the Cl- around. The other reaction is monomolecular - a keto-O taking 
> a H from a nearby amino group into an alcohol-imin as a Product.
>
> I have already tried higher values for EPS_DEFAULT (1.0E-13) and EPS_SCF 
> (1.0E-7), and nothing changes.
>
> I feel like the Dimer simply doesn't know where to stop with increasing 
> the Energy. Perhaps the choice of DFT (PBE) and basis (DZVP-MOLOPT-GTH (a 
> good basis)) is bad for the particular PES ?
>
> I would like any advises at all. Do you have success using the Dimer 
> method ? Can you provide input files from successful runs, other than the 
> ones already in the group conversations ?
>
> Best Regards,
> Dobromir
>
>
>

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