[Wien] Fwd: Fwd: Band Edge position
Peter Blaha
pblaha at theochem.tuwien.ac.at
Sat Dec 21 15:32:14 CET 2019
For ab inito calculations check out eg:
https://doi.org/10.1021/jp508880y
Am 21.12.2019 um 09:25 schrieb Gavin Abo:
> You might have a look at Eqn (6) in [1]. It looks like that is used as
> the E_CB equation in [2]. Look in [3] how pHzpc - pH = 0 in Eqn (1)
> simplifies to Eqn (2).
>
> There are three methods to determine band edge positions. Second method
> of first principle has large discrepancies between calculated and
> measured values. Third method of simple approach of Butler and Ginley
> used in [1,2] gives reasonable results [4], which validity was
> demonstrated on 11 oxides [5,6]. The method popularized by the paper of
> Xu and Schoonen [7]. The absolute electronegativity changes with the
> atoms and its elements [8,9].
>
>
> [1] https://doi.org/10.2138/am-2000-0416
> [2] http://www.rsc.org/suppdata/cp/c4/c4cp03494e/c4cp03494e1.pdf
> [3] http://www.rsc.org/suppdata/c7/cy/c7cy00393e/c7cy00393e1.pdf
> [4] https://doi.org/10.1016/j.jksus.2014.06.002
> [5]
> https://pubs.rsc.org/en/content/articlelanding/2014/CP/c3cp54589j#!divAbstract
> [6] https://doi.org/10.1063/1.5041784
> [7] http://www.rsc.org/suppdata/cc/c2/c2cc31398g/c2cc31398g.pdf
> [8] https://doi.org/10.1016/j.ceramint.2018.01.064
> [9]
> https://www.researchgate.net/post/How_can_I_calculate_absolute_electronegativity_of_CuAl2O4
>
> On 12/20/2019 9:58 AM, Subhasis Panda wrote:
>>
>>
>> ---
>>
>> 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 <mailto: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>
>> > <mailto: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>
>> > <mailto: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
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>>
>>
>>
>>
>> --
>>
>>
>>
>> Best regards,
>> ------------------------------------------------------------
>> Subhasis Panda
>> Assistant Professor
>> Department of Physics
>> National Institute of Technology Silchar
>> Assam, India - 788010.
>>
>> -------------------------------------------------------------
>>
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