Dear Lorenzo, What you have explained is not enough to be of help. Meanwhile, I think it useful to have a look at previous discussions regarding using the conservation law to easily compute the spin conductance Ref*. You see bello a small script that might be useful: syst = kwant.Builder() sym = kwant.TranslationalSymmetry(lat.vec((-1, 0))) syst = kwant.Builder(sym, conservation_law=-sigma_z) smatrix = kwant.smatrix(syst.finalized(), energy, args=(params,)) # the spin up conductance (up to up) Gup.append(smatrix.transmission((1, 0), (0, 0))) # the spin down conductance (down to down) Gdn.append(smatrix.transmission((1, 1), (0, 0))) # total conductance G.append(smatrix.transmission((1, 0), (0, 0))+smatrix.transmission((1, 1), (0, 0)))
Ref* https://kwant-discuss.kwant-project.narkive.com/ZRoAKlBg/kwant-up-down-conductance https://www.mail-archive.com/kwant-discuss@kwant-project.org/msg00483.html best; Adel Le mer. 6 mars 2024 à 16:53, Lorenzo BAGNASACCO <lorenzo.bagnasa...@sns.it> a écrit : > Hi everyone! I am a beginner Kwant consumer and, for this reason, I am > trying to "solve" very simple problems, i.e. problems for beginners. The > first one is the following: > > I have a 1D problem where basically a spin-1/2 particle crosses a region > without a potential neither magnetic fields. I am able to write correctly > the setup of the problem in Kwant. Fixed the incoming particle energy, I > find a 4 by 4 scattering matrix (this is comforting), but I do not > understand which is the protocol that Kwant uses to order the coefficients > in the scattering matrix. For example, according to the usual description > of the transmission matrix (from left-to-right), the element t_{00} > corresponding to the probability to start, for example, in the state s=-1/2 > in the left lead and arrives in the state s=-1/2 in the right lead, and > similarly for the other elements. How can I manage these labeling in my > code? > > Thank you! >
