[DFTB-Plus-User] Problem with :Relative Poisson Error: NaN"

[Gabriele Penazzi]

On 07/11/2014 09:58 PM, Enlong Liu wrote:
> Dear DFTB+ users,
>
> I want to calculation the transmission function of a contact made of
> Si slab and BNT. But in the output file, the "Relative Poisson Error"
> term gives NaN, instead of a number which is under the tolerance I set
> in the input file. And thus the transmission function gives NaN as
> well. Could any one tell me where the problem comes from?
>
> In the attachment are relative files I used to do the calculation,
> including input, output, tunnelling data and the geometry file.
>
> By the way, the input file works for previous calculation for the
> contact made of Ag and BNT, I just changed the structure and the
> corresponding partition and numbering of the geometry.

Hi Enlong,

do you use parameters from a freely distributed set? I cannot try to
replicate your calculation without parameters.

Please note that this case is quite different from Ag/BNT as metal
electrodes behaves generally better. Semiconducting ones need generally
long buffers due to the poor screening. Therefore you can expect this
calculaiton to be more tricky than Ag/BNT, even though these arguments
are more relevant with applied bias.

That said, there could be some problem in the boundary conditions as the
Poisson shouldn't behave like this. In the past weeks we spot some
problems in periodic systems. But in that case something should have
happened in the Ag/BNT calculation as well. Did you check the potential
output in the Ag/BNT calculation you made? Did you notice anything
strange there?

Cheers,
Gabriele


>
> Thanks a lot for your help!
>
> Best regards,
>
> -- 
> Faculty of Engineering at K.U. Leuven
> BIOTECH at TU Dresden
> Email:liuenlong20 at gmail.com <mailto:liuenlong20 at gmail.com>;
> enlong.liu at student.kuleuven.be
> <mailto:enlong.liu at student.kuleuven.be>;
> enlong.liu at biotech.tu-dresden.de <mailto:enlong.liu at biotech.tu-dresden.de>
> Mobile Phone: +4917666191322
> Mailing Address: Zi. 0108R, Budapester Straße 24, 01069, Dresden, Germany
>
>
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-- 
Dr. Gabriele Penazzi
BCCMS - University of Bremen

http://www.bccms.uni-bremen.de/
http://sites.google.com/site/gabrielepenazzi/

phone: +49 (0) 421 218 62337
fax: +49 (0) 421 218 62770

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