[DFTB-Plus-User] KPointsAndWeight

Bálint Aradi balint.aradi at bccms.uni-bremen.de
Thu Jan 23 09:50:20 CET 2014


Dear N.,

>
> I have built an xyz file of a model, as described below, to calculate the
> transport properties of AGNR with Na=8 with 42.458 nm length (namely 100
> unitcells), where the electrodes are AGNR with Na=8.
> - Should I get all 100 unitcells of AGNR with Na=8 as an extended molecule?
> - How to determine KPointsAndWeights?

The size of the extended molecule depends on the feature you would like
to study. If the AGNR is homogeneous at all the 42.458 nm, there is no
reason to take 100 unit cells. Just take the smallest meaningful
extended molecule and enlarge it step by step and check for convergence
of the quantity you aim for.

The KPointSampling for the contacts depend on the size of the principal
layer in the contact. By systematically increasing the K-point sampling,
you can again test, which one gives you results being convergent enough.

Best regards,

 Bálint


-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b_aradi/


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