Dear Konner, When one considers infinite lead with symmetries (e.g. particle hole), there is an amiguity in the definition of the scattering states because e.g. the linear combination particle + hole is a valid definition. Conservation laws is a way to define what you need. See the tutorial section of kwant or the corresponding section in our review: https://arxiv.org/abs/2407.16257 If you only consider the normal section of the Hamiltonian you indeed don't need this feature. Best, Xavier ________________________________ De : Konner Feldman <blackknight@feldmanfamily.net> Envoyé : lundi 28 octobre 2024 01:44:52 À : kwant-discuss@python.org Objet : [Kwant] conservation_law and particle_hole in finite systems I am trying to simulate a finite size rectangular 2d electron gas inside a josephson junction. There is one rectangular scattering region on each end that is coupled to a different superconductor, while the middle rectangular scattering region is just a part of the semiconductor 2DEG. I am only simulating the 2DEG and not the superconductors, but there is still spin-orbit coupling and hole interactions. I was told that the "conservation_law" and "particle_hole” parameters are not needed for systems such as this one that do not have infinite length regions, but I don't understand why. Could somebody please help me understand this?