[Wien] Slab Calculation

[Luis Ogando]

Dear Alonso Onofrio,

   I know some works that estimate the band alignment of two semiconductor
materials in a heterostructure using their band structure calculated for
the respective bulk systems. Despite of this, in my opinion, the accurate
way to do it is to build a "supercell" starting from one of these materials
and adding the other one along an appropriate axis.
   You have to take care to build a sufficiently large cell in order to
prevent "communication" between the same material regions in neighbour
cells. Probably, you will have also to relax atomic positions for the atoms
"near" the interface.
   After this, you may use the DOS projected on the atoms to get an idea of
the gap evolution along the axis perpendicular to the interface. As you
will see, the picture of an abrupt change of the band gap at the interface
is not real despite being very useful in approximations like "effective
mass".
   Well, it is obviously a much more computationally expensive procedure,
but I believe it is the reliable way to do it.
   Perhaps, the reference Physical Review B 79, 241312 (R) (2009) could
help you.
   All the best,
                    Luis Ogando



2013/1/23 <alonofrio at comcast.net>

> Dear Wien2K Users,
>
> I am new to Wien2k and I need help with the following.
> I am trying to get the band alignment of two semiconductor materials.
> These are 2D slabs for which I performed separate calculations and now I
> would like to compare the band edges.
> I understand that the bands and Fermi energy are calculated with respect
> to the average electrostatic potential calculated in the interstitial
> region. For these slab systems the electrostatic potential is calculated at
> Z=0 and Z=0.5 (:VZERO) from this I should be able to get the work function
> as WF=VZERO-FER.
>
> Now my question, Is it possible to compare these two separate calculations
> by means of  knowing the work funtion of both slabs? If so what would be
> the procedure to compare the band edges (VBM and CBM) for both materials
> making sure they are measured from the same reference?
>
> Thanks so much, any input or opinion is greatly appreciated.
> Alex Onofrio,
> Department of Physics
> Universidad de Los Andes
> Bogota, Colombia.
>
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