Dear all, I would like to simulate transport through a simple 1D structure, and i used chain() function to define the lattice but i dont know how to define leads. I tried to use transationalsymmetry() function but it does not work. Below i paste part of my simple code def make_system(L=100,dx=1.0,m=0.0667): lat=kwant.lattice.chain(dx) sys=kwant.Builder() sys[(lat(i) for i in range(L))]=onsite sys[lat.neighbors()]=hopping sym = kwant.TranslationalSymmetry((-dx,0)) #here i also tried to use kwant.TranslationalSymmetry((-dx)) l_lead=kwant.Builder(sym) l_lead[(lat(0,0))]=onsite l_lead[lat.neighbors()]=hopping sys.attach_lead(l_lead) sys.attach_lead(l_lead.reversed()) return sys.finalized() I would be greatfull for advises. Thank you in advance Best Regards Pawel