[Pw_forum] Transport calculation tutorials

[Gabriele Sclauzero]

Hi Zubaer,

Zubaer Hossain wrote:
> Hi,
> 
> I am interested to perform transport calculations.
> 
> I was wondering if there were any tutorials explaining 'how to's', 

To my knowledge there are no tutorials (intended as that) about conductance calculations 
with QE, so far.

> 'effects of finite cross-section of the leads, type of connection 
> between  leads and scattering region' etc. 

I think this is system specific, not QE specific. It depends of the physical system you 
want to investigate and how you want to model it.


> I read the input file 
> description for using pwcond.x; it might be useful to learn some 
> critical stuffs about transport calculation using QE e.g. 

Since Alexander will be away and busy for few days, I dare to point you to his personal 
web page (hoping he will not blame me...) that, though still under construction, has 
slides about PWCOND as well as some examples and links to all the reference papers.

http://people.sissa.it/~smogunov


> convergence of 
> transmission coe w.r.t k-points. 

Again, I think this is not specific of QE calculations, but of any other transport code 
which uses PBCs. I think you should have a look at this work by Thygesen:

in journal: Phys. rev B (ISSN: ) , vol: 72, pages: 033401-1 - 033401-4, 2005

In my limited experience with k-dependent transmission calculations, I can say that the 
number of k_perpendicular points needed to converge the transmission can vary quite a lot 
depending on the cross section of your supercell and of the number of band edges in the 
complex band structure around the scattering energy you are considering (and this makes 
the convergence somehow energy-dependent).


Regards

GS


> A brief review/hint or pointing to any 
> paper explaining details of QE calculations would have been great.
> 
> Thanks in advance,
> Zubaer
> Department of Mechanical Science and Engineering
> Univ. of Illinois at Urbana-Champaign, USA
> 
> 
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