[DFTB-Plus-User] non-scc transport calculation

Theodoros Leontiou eng.lt at frederick.ac.cy
Wed Sep 12 09:08:43 CEST 2018


Hi Gabriele, 

Thanks for your reply.  

There is a lot of literature about the NEGF formalism.  However, could
you please point out which is the most appropriate reference for the
theoretical (and perhaps technical) formalism behind the negf in dftb+ ?
 

Regards 

Theodoros 

On 2018-09-12 09:22, Gabriele Penazzi wrote:

> Hi Theodoros, 
> 
> it makes sense, but it may sound surprising depending on how you define "non-scc". In DFTB+, it means that no additional correction on the starting non-scc hamiltonian is added. Therefore density of states and transmission do not depend on Fermi level and potential. The only quantity which should show dependence on those two quantities in a non-scc calculation is the total current, as both fermi level and potential enter the Landauer formula. 
> 
> I can imagine that some other tight binding codes may define as 'non-scc' also a solution which includes somehow finite bias boundary conditions (for example, by adding non-selfconsistently a ramp potential), but this is not the case in DFTB+. 
> 
> Gabriele 
> 
> Il giorno mar 11 set 2018 alle ore 20:49 Theodoros Leontiou <eng.lt at frederick.ac.cy> ha scritto: 
> 
>> Dear dftb+ experts, 
>> 
>> I am running some non-scc transport calculations using the transportonly option. Although the results I get look reasonable there is not any dependence on the choice of the Fermi level or potential for the contacts. Is this reasonable?  
>> 
>> Best Regards 
>> 
>> Theodoros _______________________________________________
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> -- 
> 
> -- 
> Gabriele Penazzi
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