[CP2K:15] DCACP potentials

Teodoro Laino teodor... at gmail.com
Sun Apr 29 05:14:58 UTC 2007

Ciao Axel,
There's a quite big problem we discovered recently about DCACP  
potentials within cp2k..
They have a very long radius for the non-local part of the pseudo  

Now first let me express some doubt about the fitting procedures..  
how is it possible that something that should fix a short-range
behavior has a radius of several tens of Angstrom? You may argue that  
is the non-local part to have large radius.. but again this
is far from being reasonable to me...

My opinion is that the fit procedure adopted to get the DCACP  
potentials had no constraints and maybe a better and more physical  
exists for sure in which the radius of the non-local part is not such  
a huge number..

Moreover they're mostly unusable within cp2k.. Since we compute  
everything analytical (the core hamiltonian matrix) you have an  
incredible amount of periodic cells to take into account due to the  
large value of the non-local radii..

Sooooooooo.. unless you don't wanna do a PERIODIC NONE calculation  
don't be surprised to see cp2k taking ages in computing the core- 
hamiltonian matrix.. Obviously there's an elegant alternative but  
it's not implemented..
Call for volunteers?


On 28 Apr 2007, at 21:04, akohlmey wrote:

> hi all,
> we (the CMM) are current investigating currently different ways to
> improve
> the representation of dispersion forces in DFT and as one option we're
> trying the density adapted goedecker potential stuff that anatole has
> done
> while in lausanne.
> i've translated the 'library' into CP2k format and uploaded the
> resulting file
> into this google group in the hope that somebody else might find it
> useful
> (or at least will save the effort of translating it while trying it
> out).
> cheers,
>    axel.
> >

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