[DFTB-Plus-User] Ris: Question on NEGF implementation and I-V drawings

Reinaldo Pis Diez reinaldo.pisdiez at gmail.com
Tue Nov 10 20:16:31 CET 2020


Dear Alessandro

Thank you very much for your answer. I'd appreciate very much if you 
can share the code you wrote to postprocess the output obtained with 
the negf module within dftb+.

Regards,

Reinaldo

On 10/11/20 15:38, alessandro.pecchia at cnr.it wrote:
> Hi Reinaldo,
>
> The code writes a file current.dat that can be used to draw IV 
> plots. If i remember the file does not contain the bias between 
> contacts. This depends on the applied potential at each terminal 
> but also on the Fermi levels of different contacts (in case they 
> differ).
> The code does not compute an IV directly. It must be driven by an 
> external script running for different potentials.
>
> In complex system you have to ramp up the bias slowly and read 
> previously converged charges to ensure convergency.
>
> You can also approximate the IV by integrating T(E) computed in 
> equilibrium. I have some postprocess code to do this if you need.
>
> A Pecchia
>
>
>
>
> The explicit integration of
>
> Inviato dal mio dispositivo mobile Huawei
>
>
> -------- Messaggio originale --------
> Oggetto: [DFTB-Plus-User] Question on NEGF implementation and I-V 
> drawings
> Da: Reinaldo Pis Diez
> A: User list for DFTB+ related questions
> CC:
>
>
>     Dear folks,
>
>     I'm interested in obtaining I-V figures for some systems for
>     which
>     we are studying transport performance.
>
>     I was reading the paper by Pecchia et al in New Journal of
>     Physics
>     on how the NEGF method was implemented in the DFTB method and I
>     could see a lot of I-V drawings. But the tutorial at the
>     Recipes in
>     the dftb+ site shows only drawings of the transmission coeff
>     vs energy.
>
>     My question: is it possible to obtain I-V drawings using the
>     negf as
>     implemented in dftb+ 20.1 or should I obtain I(V) from the
>     transmission coeffs?
>
>     Thanks in advance.
>
>     Regards,
>
>     Reinaldo
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