Hi again, I noticed in the example code you posted that you have some magnetic field in the scattering region of your system but none in the leads. I don't know anything about what precisely you may be wanting to simulate, but in general when there are abrupt changes in the Hamiltonian you'll generate some unphysical effects in your results. If you want to be able to put magnetic field in the leads as well then read on, else ignore me :). For your case of uniform magnetic field you can choose a gauge such that the vector potential, and hence Peierls phase, is invariant by translation in the symmetry direction of your leads (if you have leads which are not all parallel to each other things become more complicated). You can then set the hoppings in the leads in exactly the same way as in the central scattering region. It seems that the Landau gauge chosen in your example code is the correct one to use when you have leads in the x-direction (as you do). Regards, Joe