you are calculating the electronic properties of the interface between ZnO and
Au(111), using an hexagonal lattice with lattice parameter 6.1413449010 au ~
3.25 A, that is the gold film is strained so as to match the ZnO lattice
parameter. The work function of gold calculated from first principles is about
5.1-5.2 eV, but with that strain it reduces to about 4.98 eV (see Table 2 of
J. Phys.: Condens. Matter 27 (2015) 015006), which is exactly what you get. So,
reverting back to your question (why if I remove some O’s in the ZnO slab
nothing changes?), it could be that the Fermi level is pinned by the metal
slab, so even if you do induce changes within the ZnO, the Au film does not
change its properties and you always “measure” the same work function (namely,
distance between the pinned Fermi level and the potential in the vacuum at the
Au side).
So, I suggest you to get help from available literature and textbooks on
Schottky (metal-semiconductor) barriers and Fermi level pinning mechanisms, to
understand the relevant properties of your system.
You might check if this answer makes sense by removing all the Zn and O atoms
from your unit cell, and recalculating the work function. Likely, you’ll not
see any change!
Hope this helps,
Giovanni
> On 18 May 2015, at 13:16, Bipul Rakshit <[email protected]> wrote:
>
> Dear Giovanni,
> I am using 8 Double layer of ZnO and 6layers of Au. and U value of 12 eV on
> Zn and 6.5eV on Oxygen. I am getting the workfunction values of 4.95 eV
> without oxygen vacancy
> and 4.96 with oxygen vacancy.
>
> The corresponding graphs I attached with it. and I also attached the input
> file where I include the dipole correction.
> I remove the oxygen from 3rd and 5th layer from Au-ZnO interface. While
> keeping the 7th and 8th layer fixed at bulk position.
>
> regards
>
> On Mon, May 18, 2015 at 1:46 PM, Giovanni Cantele
> <[email protected] <mailto:[email protected]>> wrote:
> What is the value of the work function you obtain in the two cases? Could you
> please post a plot of the electrostatic potential in the two cases, with
> relevant energies (Fermi level) highlighted?
>
> giovanni
>
> > On 17 May 2015, at 11:50, Bipul Rakshit <[email protected]
> > <mailto:[email protected]>> wrote:
> >
> > Dear users,
> > I am calculation metal (Au) - ZnO work-function. Au(111) is over the
> > ZnO(0001) surface. Since ZnO (0001) surface is polar, so i applied dipole
> > correction.
> > I am using 6Layers of Au and 8 double layer of ZnO. So is the workfunction
> > is just the difference between fermi energy Ef and the constant potential
> > in vacuum. Which i got after running pp.x and then average.x Or something
> > else.
> >
> > I am asking this because when after removing two oxygen's from ZnO's 3rd
> > and 5th layer, there is no change in the workfunction. But I am expecting a
> > change due to excess electrons of ZnO.
> >
> > --
> > Dr. Bipul Rakshit
> > Research Associate,
> > Institute of Physics (IOP),
> > Bhubaneswar- 751 005
> > Orissa
> > India
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> > <http://pwscf.org/mailman/listinfo/pw_forum>
>
> --
>
> Giovanni Cantele, PhD
> CNR-SPIN
> c/o Dipartimento di Fisica
> Universita' di Napoli "Federico II"
> Complesso Universitario M. S. Angelo - Ed. 6
> Via Cintia, I-80126, Napoli, Italy
> e-mail: [email protected] <mailto:[email protected]>
> Phone: +39 081 676910
> Skype contact: giocan74
>
> ResearcherID: http://www.researcherid.com/rid/A-1951-2009
> <http://www.researcherid.com/rid/A-1951-2009>
> Web page: http://people.na.infn.it/~cantele
> <http://people.na.infn.it/~cantele>
>
>
>
> _______________________________________________
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>
>
>
> --
> Dr. Bipul Rakshit
> Research Associate,
> Institute of Physics (IOP),
> Bhubaneswar- 751 005
> Orissa
> India
> <Without-Ovac.pdf><scf-dipole.in><With-O-Vacancy.pdf><scf-dipole-with-O-Vac.in>_______________________________________________
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--
Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: [email protected]
Phone: +39 081 676910
Skype contact: giocan74
ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.na.infn.it/~cantele
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