[CP2K:729] Re: recentering option for isolated system calculations

[teodoro laino]

Ciao Axel,
of course implementing similar options (w.r.t. the one of QMMM) (by default
set to FALSE) for the "plain" code could be a solution..
I'm back to zurich tomorrow and we can discuss together about it.

Cheers,
Teo

On Wed, Mar 5, 2008 at 2:03 PM, Axel <akoh... at gmail.com> wrote:

>
>
>
> On Mar 5, 4:13 am, Juerg Hutter <hut... at pci.uzh.ch> wrote:
> > Hi
>
> hi juerg,
>
> > the wavelet solver uses its own FFT routine. These
> > routines are the same as the FFTSG package in CP2K.
> > Yes, this is duplicating code, but it came pre-packed
> > by the developers of the wavelet solver.
> > The FFT library you choose in the input affects only
> > the FFTs in the regular CP2K code, not the wavelet solver.
>
> that is what i figured. what i don't quite understand is that
> the documentation for the wavelet solver says that one
> _has_ to use FFTSG for the rest of cp2k as well.
>
> but coming back to the initial question, do you have
> any comments on implementing a recentering of coordinates option?
>
> cheers,
>    axel.
>
> >
> > best regards
> >
> > Juerg
> >
> > ----------------------------------------------------------
> > Juerg Hutter                   Phone : ++41 44 635 4491
> > Physical Chemistry Institute   FAX   : ++41 44 635 6838
> > University of Zurich           E-mail: hut... at pci.uzh.ch
> > Winterthurerstrasse 190
> > CH-8057 Zurich, Switzerland
> > ----------------------------------------------------------
> >
> > On Tue, 4 Mar 2008, Axel wrote:
> >
> > > On Mar 4, 5:29 pm, Rad <rad.... at arl.army.mil> wrote:
> > >> Axel,
> >
> > >> I am struggling with a large isolated system and I am using the MT
> > >> poisson solver. Maybe I should try the wavelet based PS. Could you
> > >> please let me know how to set up the section and if there are any
> >
> > > syntax and parameters is in the cp2k input reference manual.
> >
> > > BTW: it would be nice to have an explanation for the requirement
> > > of FFTSG as preferred FFT, it seemed to work with FFTW3 as well and
> > > i would have expected the code to crash or refuse the run, if
> > > this was a "hard" requirement.
> >
> > >> caveats? (Teo mentioned that and I forgot the syntax) Do we have to
> > >> have
> > >> a vaccum of 20% for the wavelet method or is it only for the MT
> > >> scheme?
> >
> > > i would consider 20% vacuum (how do you compute it?) to be far too
> > > little for MT p-solver. you may get away with it if your system has
> > > favorable error cancellation, but i would not depend on it.
> >
> > > formally, the MT p-solver requires a box of twice the size of a
> > > sphere that encloses the total charge density of your molecule
> > > (i.e. atoms _and_ electron density). i can see small errors crop
> > > up on my (weakly interacting) test system starting from exactly
> > > the %50 mark and then the errors became intolerably large at
> > > having 40% vacuum.
> >
> > > cheers,
> > >    axel.
> >
> > >> Thanks
> > >> Rad
> >
>
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