[Wien] Fwd: Fwd: Band Edge position

[Subhasis Panda]

---

Dear Experts,

I wanted to calculate the absolute band edge energies for RbPbI_3 compound
only (not any interface like RbPbI3 and TiO2 interface) in the orthorhombic
phase. As already suggested, it's a computationally costly work and we
don't have enough computational facility also in our institute. I was
searching in the internet and got the following information. Looking
forward to your expert opinion.


In the following reference, using Eqn 1(a) & (b) can we estimate that? It
requires absolute electronegativity of the semiconductor and the band gap.
https://doi.org/10.2138/am-2000-0416

whereas in the following reference, the expressions are a little different.
http://www.rsc.org/suppdata/cp/c4/c4cp03494e/c4cp03494e1.pdf

Are these two expressions referring to the same thing?  If not which one
shall we use. I've one more query, does  absolute electronegativity of a
material (semiconductor) changes with its crystal structure type (like bcc,
fcc)?

Looking forward to your reply.
Thank you and best regards
Subhasis


On Fri, Dec 6, 2019 at 12:57 AM Peter Blaha <pblaha at theochem.tuwien.ac.at>
wrote:

> This is not such a simple task. You will have to create a supercell
> simulating the interface between the two materials.
>
> The answer can change depending how you form the interface. Furthermore
> this can be a complicated task, as the periodicity must fit and one has
> to test/define various surfaces/interfaces (except if 2 materials happen
> to grow nicely epitaxically).
>
> A simpler but much less accurate approach is to do 2 independent surface
> slab calculations with sufficient vacuum. From the difference of EF and
> the coulomb potential in the middle of the vacuum (:VZERO) you get an
> absolute band edge (actually this is the work function in a solid).
> However, this method neglects band bending, charge transfer or dipole
> formations at the interface, which could completely spoil the answer.
>
> Am 05.12.2019 um 11:27 schrieb Subhasis Panda:
> >
> >
> > ---------- Forwarded message ---------
> > From: *Subhasis Panda* <onnyorup.iit at gmail.com
> > <mailto:onnyorup.iit at gmail.com>>
> > Date: Wed, Dec 4, 2019 at 2:31 PM
> > Subject: Band Edge position
> > To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at
> > <mailto:wien at zeus.theochem.tuwien.ac.at>>
> >
> >
> >
> > Dear experts,
> > How can I estimate the absolute band edge position (CB/VB) of a
> > semiconductor using Wien2k?
> > The attached figure is what I'm trying to get.
> > Looking forward to your kind help.
> >
> > --
> >
> >
> >
> > Best regards,
> > ------------------------------------------------------------
> > Subhasis Panda
> > Assistant Professor
> > Department of Physics
> > National Institute of Technology Silchar
> > Assam, India  - 788010.
> >
> > -------------------------------------------------------------
> >
> >
> > --
> >
> >
> >
> > Best regards,
> > ------------------------------------------------------------
> > Subhasis Panda
> > Assistant Professor
> > Department of Physics
> > National Institute of Technology Silchar
> > Assam, India  - 788010.
> >
> > -------------------------------------------------------------
> >
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>
> --
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
> Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
> WWW:
>
> http://www.imc.tuwien.ac.at/tc_blaha-------------------------------------------------------------------------
>
>

-- 



Best regards,
------------------------------------------------------------
Subhasis Panda
Assistant Professor
Department of Physics
National Institute of Technology Silchar
Assam, India  - 788010.

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