[CP2K-user] [CP2K:14245] Re: Geometry optimisation of organic molecule on fcc Au(111) slab

[DMITRII Drugov]

thank you for reply!

Dmitrii

On Wednesday, November 18, 2020 at 8:53:56 PM UTC+11 ant... at gmail.com 
wrote:

> Dear Dmitrii,
>
> I would recommend you to abstain from manual calculations of such kind.
> Please employ any software able to generate slabs. At least at the
> beginning -- you should play with it to realize how the slab generation
> actually looks like. Use crystallographic data (you can find a plethora
> of CIF files shipped with Avogadro or use Crystallography Open Database
> to find the required CIF). Please remember that not only correct
> supercell dimensions, but also correct and complete atom coordinates are
> crucial for your task.
>
> 18.11.20 08:18, DMITRII Drugov пише:
> > Also, do you think I need to set up different GPW cutoff and
> > real_cutoff for each system individually? Or I can use one cutoff for
> > these four different surfaces to calculate adsorption of organic
> > molecule? 
>
> AFAIK there are two points in that regard:
>
> 1. You should never compare electronic energies made with different 
> cutoffs;
>
> 2. You should test the convergence of results with respect to cutoffs. I
> understand that you could quickly run out of resources if you decide to
> increase the cutoff to "real convergence" (where energy change on cutoff
> change is really negligible), but at least you should make sure that the
> cutoffs are enough to exclude drastic flaws able to provide
> qualitatively wrong results.
>
> However, it would be better if somebody more experienced comments this.
>
> > However, I saw people specify it in this way to highlight GPW method
> >     &QS
> >       METHOD GPW
> >       EXTRAPOLATION USE_GUESS
> >     &END QS
> > Do you think which one is correct for geometry optimisation?
> No difference. "GPW" is the default value for METHOD in this section,
> please refer to the manual:
> https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/QS.html#list_METHOD
> So, its explicit mention is correct but abundant.
> > For calculation of Eab, I can use total energy of system for the last
> > step of optimization? I don't need to take final structure and run
> > energy calculation again, unless I need some charge density
> > distribution etc?
>
> If you check your output file, you should find a string "Reevaluating
> energy at the minimum".
>
> Yours,
>
> Anton
>
>
>
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