[DFTB-Plus-User] contact 1 interacts with more than one PL

Gabriele Penazzi gabriele.penazzi at bccms.uni-bremen.de
Mon Jan 27 09:50:03 CET 2014


On 01/24/2014 06:16 PM, n.salami at srbiau.ac.ir wrote:
> Dear all
>
> Good time,
>
>
> I have built an xyz file of a model, as described below, to calculate the
> transport properties of AGNR with Na=8 , where the electrodes are AGNR
> with Na=8.
> I got 14 unitcells of AGNR nanoribon as device and 2 unitcells of AGNR
> nanoribon as source (drain) electrode.
> while running the device, I have occurred to bellow error :
>
[cut]
> Could you guide me, Please?
> How to can solve this problem?

Hi,
you should attach the gen file.

The reason is probably that the principal layer is too short. As
specified in the online cookbook " In practice these layers must contain
a sufficient number of atoms in order to ensure that Hamiltonian and
overlap interactions with second neighbouring PLs vanish or can be
considered negligible" .

The error message means that the second principal layer of the contacts
has nonzero interaction with the device region, and it shouldn't be like
that.

If that's the case, you can solve by doubling the starting layer. It is
a good idea to have a layer which is 5 or 6 Angstrom long, to be on the
safe side. Therefore you'll need a 32 atoms PL instead of a 16 one. I
attach an xyz and gen of a single layer as an example. You can try to
run the buildwire utility on this layer and check the graphene
nanoribbon example provided with the code.

Gabriele


>
> Thanks in advance,
> Bests Regards.
> Nadia Salami
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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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