TranslationalSymmetry does not work with my SimpleSite Family. Therefore, I attach the leads manually. I Use class kwant.builder.BuilderLead(builder, interface). I define a builder in the following way: #The tight-binding system of a left lead. left_lead = kwant.Builder() #Add sites lead left_lead[lat(x1, y1)] = 1.5 left_lead[lat(x2, y2)] = 1.5 etc #Add hoppings left_lead[lat(x2, y2), lat(x1, y1)] = 2j etc The same way I define the interface(wich called left_sequence) but without the hoppings. l_lead = kwant.builder.BuilderLead(left_lead, left_sequence). But it does not work. Where I'm wrong? As the lead I want to use the left and right boundary of my graphene atoms. С уважением, Татьяна Григоренко