[DFTB-Plus-User] .cube file

Vladimir Yushkevich yushkevich.v.n at gmail.com
Thu Dec 9 19:31:28 CET 2010


Dear Bálint,

Thank you, the previous suggestion has helped.  Now I can to obtain EP in my
supercell containing the surface slab by myself just using net atomic
charges. I also need the EP in presence of external field (I include
external field in my calculations by placing point charges on the top layer
of my slab). But if I set the Charge value in Hamiltonian is non 0 it also
means that my surface is charged. What is the difference between this
approaches (except the number of electrons = const)? I noticed that
inclusion of point charges doesn't  change Mulliken charges of atoms
significantly. For this reason obtained EP for charged surface is slightly
differ than for neutral one (that looks strange). I afraid that something I
do completely wrong either by including external field or by calculating EP.


Best regards, Vladimir

2010/11/25 Bálint Aradi <balint.aradi at bccms.uni-bremen.de>

> Dear Vladimir,
>
> > My problem is that I have only cube file only for the density. For this
> > reason I have to get cube file for EP by making transformation density
> into
> > potential. And this task is complicated due to periodic boundary
> conditions
> > for surface slab.I decided to ask somebody who has experience in
> analysing
> > of EP.
>
>  Indeed, DFTB does not produce a cube file for the electrostatic
> potential. However, you can produce it yourself, by taking the
> Mullikan-charges on the atoms, and adding up the appropriate (delta Q/r)
> contributions. Since every charge is treated as a spherical symmetric
> point charge, summing up the (delta Q/r) contribution from all atom in a
> certain space point should give you a sort of EP.
>
>  Best regards,
>
>  Bálint
>
> --
> Dr. Bálint Aradi
> Bremen Center for Computational Materials Science, University of Bremen
> http://www.bccms.uni-bremen.de/en/~b_aradi<http://www.bccms.uni-bremen.de/en/%7Eb_aradi>
>
>
>
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