Dear Sir, I am new to kwant. How to attach a lead to a particular portion(upper side of the square) of the honeycomb structure. sym1 = kwant.TranslationalSymmetry(lat.vec((0,1))) lead1 = kwant.Builder(sym1) def lead2_shape(pos): x, y = pos return 0<x<10 lead1[lat.shape(lead2_shape, (2,0))]=3 lead1[lat.neighbors()] = -1 I used the above code to attach the second lead but it didn’t attach to the correct place. I want to attach the lead to the upper side of the square. main code Wnr=10 lnr=10 a=1 lat=kwant.lattice.honeycomb(a) def rect(pos): x,y=pos return 0<x<lnr and 0<y<Wnr model1 = kwant.Builder() model1[lat.shape(rect,(1,1))] = 3 model1[lat.neighbors()] =-1 ##########lead shape function def lead1_shape(pos): x, y = pos return 0 < y < 10 def lead2_shape(pos): x, y = pos return 0<x<10 ##########1st lead########## sym = kwant.TranslationalSymmetry(lat.vec((-1,0))) #from the left sym.add_site_family(lat.sublattices[0], other_vectors=[(-1, 2)]) sym.add_site_family(lat.sublattices[1], other_vectors=[(-1, 2)]) lead = kwant.Builder(sym) lead[lat.shape(lead1_shape, (1,1))]=3 lead[lat.neighbors()] = -1 model1.attach_lead(lead) ##########problem in 2nd lead, from this below code it attach to other position########## sym1 = kwant.TranslationalSymmetry(lat.vec((0,1))) lead1 = kwant.Builder(sym1) lead1[lat.shape(lead2_shape, (2,0))]=3 lead1[lat.neighbors()] = -1 model1.attach_lead(lead1) kwant.plot(model1) Anyone, please help please see this image in below link, I want to attach the second lead in the red-circled position of the figure https://drive.google.com/file/d/15ORyo4j_tAvgC8jaT5lQxmQNS6e0QoOF/view?usp=s...