[DFTB-Plus-User] waveplot

[Vladimir Yushkevich]

Hi Ben,

I want to obtain work function for surface. The technique combines the mean
electrostatic potential step across the slab surface with the Fermi energy
of a bulk crystal (the reference paper is
http://iopscience.iop.org/0953-8984/11/13/006). For construction of EP I
need the total charge density. I can’t obtain consistent results with
reference paper. My problem is the wrong EP distribution or Fermi level for
bulk.


2011/6/1 Ben Hourahine <benjamin.hourahine at strath.ac.uk>

> On 01/06/11 17:46, Vladimir Yushkevich wrote:
> >
> > Dear DFTB+ users,
> >
> > By using waveplot I obtain total charge density (according to manual).
> > Indeed, I think it is electronic charge density (integration over all
> > volume of supercell produces the total number of electrons in my
> > system). Then in my calculations ionic charge density is added as a
> > set of point charges. Now I can get "total charge density" (sum of
> > electronic and ionic parts) and analyze the average distribution over
> > one of Cartesian coordinate. My problem is that point charges cause
> > cusps near atomic positions. I suppose that point charges in DFTB+
> > code approximated by (for example) Gaussian function.
> >
> > I need to know what function is used for approximation of spatial
> > distribution of the nuclear charge and core electrons?
> >
> >
> >
> > --
> > Best regards, Vladimir Yushkevich
> >
>
> Hello Vladimir,
>
> The number of electrons is only those in valence states, and the
> waveplot density is from
> only these electrons, the core states and nuclear charge are not
> provided. For the standard
> non-relativistic parameters, the nuclear charge is at a point and the
> core states are atomic
> Kohn-Sham orbitals, but these are discarded during the parameterization
> (most standard
> parameters use atomic Slater orbitals as a basis so the cusp is
> implicitly present). Can
> you explain what property you are calculating that requires the total
> density?
>
> Regards
>
> Ben
>
> --
>      Dr. B. Hourahine, SUPA, Department of Physics,
>    University of Strathclyde, John Anderson Building,
>           107 Rottenrow, Glasgow G4 0NG, UK.
>     +44 141 548 2325, benjamin.hourahine at strath.ac.uk
>    The University of Strathclyde is a charitable body,
> registered in Scotland, with registration number SC015263
>
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-- 
Best regards, Vladimir Yushkevich
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