[Pw_forum] charge analysis

[Giuseppe Mattioli]

Dear Jure and Axel
Axel is right. A smooth charge density including core electrons yields best results, specially if the pseudopotential core region is somehow entangled 
with the assignment of a given set of grid points to the Bader's volume of a given atom. Notwithstanding (at least in my experience):

a) if you use PAW pseudopotentials you can extract a reconstructed and smooth all-electron charge density by using the plot_num=17 option of pp.x, 
together with a *very dense* real space grid (2 or 3 times the grid you find in the pw.x output). In this way you generally crunch reliable Bader's 
numbers.

b) the same holds for *reasonably hard* NC pseudopotentials, where any overlap between core regions and density minima is unlikely.

Remember then to perform a last scf calculation after, e.g., a standard "relax" calculation, using high values of nr1, nr2 and nr3 (beware of memory 
usage...), before post-processing the charge density to produce the cube file.

HTH

Giuseppe

On Monday, July 27, 2015 03:16:32 PM Jure Varlec wrote:
> On Mon, 27 Jul 2015 06:54:08 -0400
> 
> Axel Kohlmeyer <akohlmey at gmail.com> wrote:
> > please note that this procedure is missing the contributions from the
> > core electrons of the pseudopotentials and thus the results may be off
> > or completely bogus.
> 
> I don't understand why this should happen. Bader's method looks for
> surfaces of minimal charge density between atoms. What do core
> electrons have to do with this? Please clarify.
> 
> Thank you,
> 
> Jure
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   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
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