[DFTB-Plus-User] Setting non-periodic boundaries using a vacuum region

[Benjamin Hourahine]

You can of course set the twist angle for the helix to be 0, in which case this geometry will be a 1D wire.

However, SCC and also a number of other code features are not currently available for this boundary condition.

Regards

Ben

       Dr. B. Hourahine, SUPA, Department of Physics,
     University of Strathclyde, John Anderson Building,
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     +44 141 548 2325, benjamin.hourahine at strath.ac.uk

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From: DFTB-Plus-User <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> on behalf of Bálint Aradi <aradi at uni-bremen.de>
Sent: 05 January 2022 19:30
To: dftb-plus-user at mailman.zfn.uni-bremen.de <dftb-plus-user at mailman.zfn.uni-bremen.de>
Subject: Re: [DFTB-Plus-User] Setting non-periodic boundaries using a vacuum region

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>
> 1. For the case of a single nanowire, would the `H` boundary condition
> be suitable? What is meant by helical cells?

Helical is usually applicable, if your system must be translated and
rotated, when going from one unit cell to the others. Nanowires in
general have a simple translational symmetry. You would rather have to
choose 3D periodicity with vacuum in the non-periodic directions. (The
same holds for a 2D systems.) You can take arbitrary amount of vacuum,
in DFTB it is for free. (Take 50 or 100 Angstrom).

Best regards,

Bálint


--
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
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