[Pw_forum] Dipole correction in superlattice with no vacuum

[stefano de gironcoli]

if a dipole layer develops at the interface (likely to occur when you 
put together atoms with different charges and electro-negativity) a step 
in the electrostatic potential would result... which directly shifts 
your band-offset.
think of how you can modify the workfunction of a surface (which is the 
band offset between the material and vacuum) by adsorbing polar 
molecules or anything that create a dipole layer.

interface interminxg dependence in heterovalent junctions have been 
studied extensively (among many others) by Maria Peressi. You may wont 
to read some of her works starting with

1.
Band engineering at interfaces: theory and numerical experiments
By: Peressi, M; Binggeli, N; Baldereschi, A
JOURNAL OF PHYSICS D-APPLIED PHYSICS  Volume: 31   Issue: 11 Pages: 
1273-1299   Published: JUN 7 1998

2.
LOCAL INTERFACE COMPOSITION AND BAND DISCONTINUITIES IN HETEROVALENT 
HETEROSTRUCTURES
By: NICOLINI, R; VANZETTI, L; MULA, G; et al.
PHYSICAL REVIEW LETTERS  Volume: 72   Issue: 2   Pages: 294-297 
Published: JAN 10 1994

3.
TUNING BAND OFFSETS AT SEMICONDUCTOR INTERFACES BY INTRALAYER DEPOSITION
By: PERESSI, M; BARONI, S; RESTA, R; et al.
PHYSICAL REVIEW B  Volume: 43   Issue: 9   Pages: 7347-7351 Published: 
MAR 15 1991

HTH

stefano


On 06/06/2016 12:37, Dae Kwang Jun wrote:
> Dear Professor Gironcoli,
>
> Thank you for your time. I do not think I understand the dependence of 
> the band offset in the interface. From what I understand, band offset 
> calculations are obtained from the average potential in the bulk 
> region and bulk band edges (or core levels). I have seen many journals 
> that state the interface structure is important, and I know they 
> should be. However, I do not know how the structure of the interface 
> affects the band offset if only the bulk band edges and bulk average 
> potetential are used to calculate it. Could you recommend me a 
> reference that explains this? Most references that I have found show 
> how defects and strain influence the band offset but do not explain why.
>
> Thank you in advance,
>
> Dae Kwang Jun
>
> On Sun, Jun 5, 2016 at 5:21 PM, Stefano de Gironcoli 
> <degironc at sissa.it <mailto:degironc at sissa.it>> wrote:
>
>     ... However in the case of band lineup between heterovalent
>     material band offset is strongly dependent on details of the
>     interface.. So I don't know how meaningful the calculation can be.
>
>     stefano
>     (sent from my phone)
>
>     > On 05 Jun 2016, at 10:17, Stefano de Gironcoli
>     <degironc at sissa.it <mailto:degironc at sissa.it>> wrote:
>     >
>     > I think one could use the electric field option putting a dipole
>     layer deep in the bulk of one of the two materials (maybe the
>     metal) and monitor when the macroscopic average of the
>     electrostatic potential is horizontal in the oxide to obtain the
>     electrostatic lineup.
>     >
>     > stefano
>     > (sent from my phone)
>     >
>     >> On 05 Jun 2016, at 07:29, Dae Kwang Jun <jdaekwang at gmail.com
>     <mailto:jdaekwang at gmail.com>> wrote:
>     >>
>     >> Dear all,
>     >>
>     >> I am trying to find the band offset between a polar metal oxide
>     and a metal. Is it possible to make a dipole correction without
>     any vacuum in the superlattice or supercell?
>     >>
>     >> Sincerely,
>     >>
>     >> Dae Kwang Jun
>     >> _______________________________________________
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>
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