[Pw_forum] transmission calculation

[Manoj Srivastava]

Dear Gabriele,
Thanks for answering. 
On Thu, 30 Apr 2009, Gabriele Sclauzero wrote:

> Manoj Srivastava wrote:
> > Dear PWSCF users and developers,
> >  I have tried to do a transmission calcuation and not getting right
> > results. I have tried to figure out the reason behind this and realized
> > that in my set up for some reason the Bloch waves in left lead get changed
> > resulting wrong transmission. By this I meant that, if I just try to
> > calculate complex band of the left lead, I have a kz for each kx,ky and E
> > but when I am doing transmission calculation, the Bloch's wave in the same
> > lead has different kz for the same kx,ky and E, which does not make sense
> > as why should the Bloch's wave in lead get affected by the presence of
> > scattering region? For the right lead kz remains the same in both cases
> > though, which I believe how it should be. 
> 
> Does it happen also when you do not use G_perp basis reduction? Can you try again the CBS 
> and the transmission calculation without specifying ecut2d, nz1 and putting ewind=1.d3?

Yes, I have tried this. No difference, the kz value for left lead gets
changed, when i switch from ikind=0 to ikind=2.

> 
> Better, first check the size of the reduced basis using
> 
> grep n2d <output file from transmission> <output file from CBS>
> 
> and see if they are very different (or if the second is too low with respect to the size 
> of the whole basis set).
> Also try to understand which of the two results (kz vectors) is correct, by comparing the 
> real part of kz with the band structure from pw.x

The one with ikind=0 is correct.

> 
> 
> GS
> 
> 
> >  I did this for several cases, I interchanged right and left leads,
> > increased number of atoms in the scattering region, chose scattering
> > region in different way, and everytime kz of left lead changes. Following
> > is my input file for the scattering region - 
> > 
> > scf part -
> > 
> > &control
> >     calculation='scf'
> >     pseudo_dir = '/home/manoj/espresso-4.0.1/pseudo',
> >     outdir='./',
> >     prefix='cus',
> >  /
> >  &system
> >     ibrav =0,
> >     celldm(1)=4.82,
> >     nat= 10,
> >     ntyp= 1,
> >     ecutwfc =50.0,
> >     occupations='smearing',
> >     smearing='gaussian',
> >     degauss=0.02,
> >     ecutrho=500
> >  /
> >  &electrons
> >     conv_thr = 1.0e-8
> >     mixing_beta=0.7
> > /
> > ATOMIC_SPECIES
> >  Cu 63.55  Cu.pz-d-rrkjus.UPF
> > ATOMIC_POSITIONS
> >   Cu  0.0   0.0         0.0
> >   Cu -0.5   0.288675134 0.816496581
> >   Cu -1.0   0.577350269 1.632993162
> >   Cu -1.5   0.866025404 2.449489743
> >   Cu  0.0   0.0         3.265986324
> >   Cu  0.5  -0.288675134 4.082482905
> >   Cu  1.0  -0.577350269 4.898979486
> >   Cu  1.5  -0.866025404 5.715476066
> >   Cu  1.0  -0.577350269 6.531972647
> >   Cu  0.5  -0.288675134 7.348469228
> >  K_POINTS (automatic)
> > 6 6 4 1 1 1
> > CELL_PARAMETERS {hexagonal}
> >  1.0   0.0         0.0
> > -0.5   0.866025403 0.0
> >  0.0   0.0         8.16496581
> > 
> > 
> > 
> > conductance part -
> > 
> > &inputcond
> >     outdir='./'
> >     prefixl='cul'
> >     prefixr='cur'
> >     prefixs='cus'
> >     tran_file ='trans.twin'
> >     ikind=2
> >     ecut2d=50
> >     energy0=0.0
> >     denergy=0.0
> >     ewind=5.d0
> >     epsproj=1.d-6
> >     nz1=25
> >  /
> >   2
> >   0.000000       0.000000               1
> >   0.5000000     -0.5000000               1
> > 
> > 1
> > 0.0
> > 
> > Thank you for your attention. 
> > 
> > Regards, 
> > Manoj Srivastava
> > Graduate Student
> > Department of Physics
> > University of Florida, Gainesville, FL
> > 
> > _______________________________________________
> > Pw_forum mailing list
> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum
> > 
> 
> -- 
> 
> 
> o ------------------------------------------------ o
> | Gabriele Sclauzero, PhD Student                  |
> | c/o:   SISSA & CNR-INFM Democritos,              |
> |        via Beirut 2-4, 34014 Trieste (Italy)     |
> | email: sclauzer at sissa.it                         |
> | phone: +39 040 3787 511                          |
> | skype: gurlonotturno                             |
> o ------------------------------------------------ o
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>