Dear Shivang,

To get the matrix Gamma you can do:

sys            =  sys.finalized()

lead_L       =  sys.leads[0]

Sigma_L    =  lead_L.selfenergy(energy)

Gamma_L  =  -2*imag(Sigma_L)

You can find the details in this answer by Joseph [1].
To get directly the transmission matrix t you can do:

t=kwant.smatrix(sys,energy, out_leads=[1], in_leads=[0]).data          #I suppose you have just two leads.

Now, since your aim is to get the wave function, the module kwant.wavefunction gives you the wavefunction as a complex number (module and phase). So, your claim that you are unable to get the phase is confusing!

I hope this helps.
Adel

[1] https://mailman-mail5.webfaction.com/pipermail/kwant-discuss/2015-May/000355.html

Abbout Adel

On Wed, Jun 6, 2018 at 11:53 PM, Shivang Agarwal <shivang.agarwal@iitgn.ac.in> wrote:

Hello authors,

I am trying to perform an eigenchannel analysis of a graphene nanoribbon. For that I will be using the formula :

T(E) = ГL(E)½ GC†(E) ГR(E) GC(E) ГL(E)½

where ГL(E) is the coupling matrix between the left lead and the conductor, GC(E) is the greens function matrix of the conductor (system) and '†' is the dagger operator. The equation is from the following paper: https://journals.aps.org/prb/pdf/10.1103/PhysRevB.73.075429

(1) Now as far as I know, Kwant allows us to calculate transmission as a number T(E). What I need for my code is 't' where Trace(t†t) = T(E). Could somebody let me know how can I get the desired quantity 't'?. But I don't know how I can get the coupling matrix ГL(E) between the left (or right) lead and the conductor

(2) Also, we know that t = ГL(E)½ GC(E) ГR(E)½ .But I don't know how I can get the coupling matrix ГL(E) between the left (or right) lead and the conductor. Is it possible to get too?

PS - My aim is to find the wavefunctions inside the nanoribbon (which Kwant can do very conveniently) and also their phases! I have found the wavefunctions but am unable to find their phases. If there's any other way to find it that would also be extremely helpful.

Any help would be greatly appreciated.

Thanks and Regards,

Shivang Agarwal

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Shivang Agarwal

Junior Undergraduate

Discipline of Electrical Engineering

IIT Gandhinagar

Contact: +91-9869321451

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Abbout Adel