[CP2K:2276] Re: cp2k and Bader analysis

Ondrej Marsalek ondrej.... at gmail.com
Fri Sep 18 15:14:50 CEST 2009


On Fri, Sep 18, 2009 at 15:03, Axel Kohlmeyer <akoh... at gmail.com> wrote:
>
>
> On Sep 18, 5:59 am, Ondrej Marsalek <ondrej.... at gmail.com> wrote:
>
> dear ondrej,
>
>> Dear Jörg,
>>
>> the implementation of Bader analysis that you can find here:
>>
>> http://theory.cm.utexas.edu/bader/
>>
>> can use Cube files as input. You can save volumetric data (for example
>> the density and KS orbitals) from CP2K into Cube files, so you should
>> be fine. The density is straightforward, if you want to do something
>
> not quite. for AIM you need the _complete_ wavefunction, whereas
> cp2k usually only outputs the valence part (even with *PAW) and
> that can have a significant impact on the validity and accuracy
> of the results. so you have to first add the core wavefunction
> part back that is subtracted out during pseudopotential generation
> or through the PAW procedure.

OK, I thought it is safe to add the cores to their atoms (as they
would be always localized in one of the partitions) to get the correct
total charge. But I have never needed AIM myself, so I have no
practical experience with this.

So doing Bader analysis on the valence density is no good, even with
norm-conserving PP? I would only expect this to be a problem with USPP
or the PAW transformation, but as I said, no experience in this.

> matthias krack once implemented a feature that you can do this
> from GPAW, but it turned out to be extremely slow and had artefacts
> that threw the bader code from the group in texas off.
>
> i have been toying with the idea of constructing density files
> to add to the existing valence density after the fact, by taking
> the difference from a single atoms all-electron and pseudopotential
> calculation, and then adding them to the valence density cube.
> but that scheme only worked for me to some degree for s-electrons.
>
>> with orbitals, you would perhaps need to use some Cube file
>> manipulation program to obtain the densities from individual KS
>> obrbitals first.
>
> why the individual KS orbitals? AIM only works on the total density,
> IIRC.

That's right, AFAIK. I was not sure wheter the wavefunction mentioned
in the original post was not meant to be a KS wavefunction. Also, you
might want to partition the spin density as well, which in ROKS is the
density of the SOMO. I thought that perhaps someone has some use (that
I am unaware of) for the partitioning of other orbitals as well.

Ondrej


> cheers,
>    axel.
>
>>
>> Best regards from Prague,
>> Ondrej
>>
>> On Fri, Sep 18, 2009 at 11:15, Jörg Saßmannshausen
>>
>> <jorg.sassm... at strath.ac.uk> wrote:
>>
>> > Dear all
>>
>> > I was wondering whether it is possible (at least in theory) to use cp2k to
>> > generate the wavefunktion-file for Bader's AIM analysis.
>> > So basically I would need an ASCII file, similar to the uploaded file (which
>> > is the file for propene). Is that possible at all with cp2k or as we are
>> > using plane waves here not possible?
>>
>> > The file location is:
>> >http://groups.google.com/group/cp2k/web/bader-aim-file.wfn
>>
>> > All the best from Glasgow!
>>
>> > Jörg
>>
>> > --
>> > *************************************************************
>> > Jörg Saßmannshausen
>> > Research Fellow
>> > University of Strathclyde
>> > Department of Pure and Applied Chemistry
>> > 295 Cathedral St.
>> > Glasgow
>> > G1 1XL
>>
>> > email: jorg.sassm... at strath.ac.uk
>> > web:http://sassy.formativ.net
>>
>> > Please avoid sending me Word or PowerPoint attachments.
>> > Seehttp://www.gnu.org/philosophy/no-word-attachments.html
> >
>



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