Hi Joe, Thank You for the answer. I definitely want to read that chapter of the Datta's book. But now my question it seems about Kwant's functional, i.e. is it possible to calculate with it the transmission (in the sense of probability) through the barrier (single and double)? So, if the Landauer's formula gives the conductivity as G=2e^2/h * T(E) * M(E) (for zero temperature), where M is the number of opened modes, and T is the transparency, in my present understanding, Kwant calculates somewhat like T(E) * M(E), but can it give me just T(E)? Sincerely, Jambulat 2017-03-27 16:26 GMT+03:00 Joseph Weston <joseph.weston08@gmail.com>:
Hi,
This means that kwant takes into account also some regions outside the leads e.g. bulk metal contacts.
As a result some dependence on E is obtained even for the case of zero depth of the potential whell and it is not identically one.
So, is it possible to obtain in Kwant the transmission coefficient through the defined in the scattering region structures which is not affected by anything else?
You have created a system with a finite width of N sites, which means that in general there will be a finite number of propagating modes open at a given energy. As there is no backscattering in the system I expect the transmission to be equal to the number of propagating modes open at a given energy, which is indeed what I see when I run your code.
You appear to be confused about the definition of transmission. It is not a probability and so is not bound to the interval [0, 1]. You may want to read chapter 3 of the book "Electronic Transport in Mesoscopic Systems" by S. Datta for an introduction to the formalism that Kwant is based on.
Happy Kwanting,
Joe