[Wannier] Cu2ZnSnSe and Cu2ZnSnS (Boltzwann Calculations)

[Alex Gal Aziz]

Thanks for the message,


I have done a check with one calculation with BoltzTRAP and Boltzwann using PBE+U. Although the trend seems to be the same, the values are not really the same. The BoltzTRAP calculation gives values about 100 ?V/K higher. Around 500 ?V/K for BoltzTRAP compared to 400 ?V/K for Boltzwann.


I believe the error must be on my part, but changing the number of WF doesn't change the result. I have kept the Bandstructure frozen till about 1 eV above the lowest conduction band.


Any ideas would be welcome.


Thanks


Alex Aziz

PhD Student

University of Reading


________________________________
From: Wannier <wannier-bounces at quantum-espresso.org> on behalf of Nicki Frank Hinsche <nicki.hinsche at physik.uni-halle.de>
Sent: 01 September 2016 21:38
To: wannier at quantum-espresso.org
Subject: [Wannier] Cu2ZnSnSe and Cu2ZnSnS (Boltzwann Calculations)

Hej Ali,

this depends heavily on the charge carrier concentration. The difference due to bipolar effects will be way more pronounced at high temperatures and/or low charge carrier concentrations. The size of the gap merely plays a role in the degenerate limit.

bests
Nicki

--------------------------------------------------------
Nicki Frank Hinsche, Dr. rer. nat.
HC Ørsted Postdoc
CAMd, Technical University of Denmark
Fysikvej, Bld. 307, Room 208
2800 Kgs. Lyngby, Denmark
Tel.: ++45 45 25 31 84
--------------------------------------------------------

> Message: 1
> Date: Thu, 1 Sep 2016 10:03:04 +0000
> From: Alex Gal Aziz <A.G.Aziz at pgr.reading.ac.uk>
> To: "wannier at quantum-espresso.org" <wannier at quantum-espresso.org>
> Subject: [Wannier] Cu2ZnSnSe and Cu2ZnSnS (Boltzwann Calculations)
> Message-ID:
>        <VI1PR0101MB2365665CF6E0025C9742F44AD1E20 at VI1PR0101MB2365.eurprd01.prod.exchangelabs.com>
>
> Content-Type: text/plain; charset="iso-8859-1"
>
> I am investigating Cu2ZnSnSe4 and Cu2ZnSnS4.
>
>
> I have been using VASP compiled with Wannier functions to generate the initial projections and then generate the MLWF using the Disentanglement procedure. I have checked the band structures and they look correct with the appropriate band gaps (~1.5 for Cu2ZnSnS4 and 0.9 Cu2ZnSnSe4).
>
>
> When I check the Seebeck using BoltzWann I seem to get similar results in both cases. I am trying to figure out if this seems plausible due to the difference in band gaps.
>
>
> Any suggestions would be welcomed
>
>
> Thanks
>
> Alex Aziz
>
>
> PhD Student
>
> Department of Chemistry, University of Reading
> Whiteknights, Reading RG6 6AD

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