[CP2K:813] Re: how to get the "total" electron density

Fawzi Mohamed fa... at gmx.ch
Thu Mar 13 10:12:33 UTC 2008

On Mar 13, 2008, at 9:23 AM, Matthias wrote:

> Hi Axel,
> indeed, the all-electron density is available with GAPW, but only in
> Fourier space as it is needed for the calculation of the X-ray
> diffraction spectrum. In principle one could perform a back
> transformation to real space using FFT and print it as a cube file.
> However, for numerical reasons you would apply in this way a low pass
> filter to the all-electron density and thus you would not obtain the
> true all-electron density in real space.

actually I think that this is the correct thing to do, we should  
maybe do something like this also instead of the stride (or at least  
do some mean).

direct collocation of the gaussians (and also stride as now done) do  
not conserve the total density when the cutoff is not high enough  
(basically always with GAPW).


> cheers,
> Matthias
> On Mar 13, 2:30 am, Axel <akoh... at gmail.com> wrote:
>> hi everybody,
>> would there be a way to get the total _electron_ density from
>> quickstep GPW/GAPW calculations?
>> i actually found a flag to output a 'total density', but that turned
>> out to be the valence electron
>> density plus the (smeared out?) core charge density, with the odd  
>> side
>> effect that the cores were
>> negative and the electrons positive. i guess it does not really
>> matter, but...
>> for all-electron GAPW calculations, this information should - in
>> principle - be available.
>> the question is, would it be much effort to put it into a cube file?
>> for pseudopotential based calculations, be it GPW or GAPW one could
>> just use the
>> density that was "removed" during pseudopotential generation.
>> any comments or suggestions would be highly appreciated.
>> cheers,
>>    axel.

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