Hi Gabriel, The error you get is related to the fact that you are using lat (which is a 'Polyatomic' object and is not callable) to fill the onsite values in the lead. You may instead consider defining the onsite values for each sub-lattice exactly as you did for syst. lead1[a(0, 0)] = … lead1[b(1, 0)] = …
This way it should work. Regards, Ousmane
