Hi, To explain what I mean. I have a system where I have separated spin-up and spin-down into two lattices (like electron and hole in the example at the kwant site) so that it is would be easier to extract spin-resolved information (G_up/up, Gup/down etc.). In addition, these two lattices consists of two sublattices (A and B). The code is like this lat_up = kwant.lattice.general([(1,0),(s,c)],[(0,0),(0,1/sqrt(3))], name='up') A_up, B_up = lat_up.sublattices lat_down = kwant.lattice.general([(1,0),(s,c)],[(0,0),(0,1/sqrt(3))], name='down') A_down, B_down = lat_down.sublattices What I want to do now, is to add a hopping term between say A_up (i,j) and B_down (i.j). So a hopping term between the two different lattices and sublattices. How can I implement this? Or is there a better way to achieve what I want? Best Camilla Espedal