[CP2K:2038] Re: optimisation problem of F compound

[Jörg Saßmannshausen]

Dear Fawzi,

I actually did:

cutoff energy
400  -183.5957955549
450  -183.5944280905
500  -183.5937679158
550  -183.5935371009
600  -183.5938000945

one of the things I learned from Rachel at the workshop :-)

For me it looked like that 500 seems to be ok, so I decided to go for that 
value.
However, these values were for the DZVP-ALLELECTRON basis set. I did not run a 
test for the aug-DZVP-GTH, simply assuming as I did not change the potential 
only the basis set the difference would be not that big? Or was that a wrong 
assumption? What cutoff would you recommend?

Thanks for the prompt reply!

All the best from a wet Glasgow!

Jörg


On Donnerstag 23 April 2009 Fawzi Mohamed wrote:
> I would say that the cutoff of 500 might be too small for the F
> element. Have you tested the cutoff needed for it?
>
> Fawzi
>
> On 23-apr-09, at 18:12, Jörg Saßmannshausen wrote:
> > Dear all,
> >
> > I am struggling to optimise a molecular structure with a F atom in it.
> > Whereas I manage to get the optimisation converged, the frequency
> > calculation clearly indicates I am not at the local minimum. Replacing
> > the F atom in the molecule with H (and leave everything else the same)
> > results in a converged structure. I got the gutt-feeling that the
> > problem is the basis set / pseudopotential I am using for F. Would
> > somebody mind to give me a helping hand here?
> >
> > I have enclosed the following files:
> > - mol file of the frequency calculation (so you see what I mean)
> > - force_eval section
> > - subsys section
> > - fluor-geo.inp
> > - fluor-freq.inp
> >
> > I had no problems with the molecule using a different program, so I am
> > quite confident about the structure. Note: it is a cation, I left the
> > anion out for computational reasons.
> >
> > Thanks for your help!
> >
> > Jörg