[Pw_forum] Slow calculation of (5, 5) CNT transmission and complex bands.

Gabriele Sclauzero gabriele.sclauzero at epfl.ch
Tue Aug 2 11:56:22 CEST 2011

Il giorno 29/lug/2011, alle ore 21.16, chengyu yang ha scritto:

> Dear All,
>          After two hours , my transmission calculation comes out a result.

And you couldn't wait for a couple of hours before writing to the forum saying that you were in trouble?...

Assuming that your PWscf calculation has been converged, the important thing here is to look at the basis set reduction performed by PWcond:

 ngper, shell number =         2809         299
 ngper, n2d =         2809         472

It looks to me that the n2d could be too small compared to the original size of the basis set (ngper). As I wrote in my previous email, you should try to decrease epsproj and check that the results (i.e. the complex bands) do not change appreciably. The eigenvalues at real k from PWcond need to be on the top of the band structure computed with PWscf.
Also compare with previous theoretical results, I guess that there should be several works about the conductance of CNTs.
cuplot is needed only to plot the scattering states. I guess that you do not need them at this stage.



> But I thought it may be not converged and didn't get the final result.
> May anybody have a look at my output file? I attached in this email.
>        My input file is like this:
>        &inputcond
>     prefixl='55'
>     tran_file='trans.cnt55',
>     ikind=0
>     energy0=4.d0
>     denergy=-0.1d0
>     ewind=3.d0
>     epsproj=1.d-4
>     delgep = 1.d-9
>     cutplot = 3.d0
>  /
>     1
>     0.0 0.0 1.0
>     5
> Is there somebody that can give me an advice?
> I really appreciate it.
> Chengyu Yang
> Materials Science and Engineering, 
> University of Central Florida, USA
> <transmission calculation>_______________________________________________
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§ Gabriele Sclauzero, EPFL SB ITP CSEA
   PH H2 462, Station 3, CH-1015 Lausanne

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