Dear Kwant Developers,

I understand that a symmetry operator (the conservation law) can be used to block diagonalize the lead hamiltonian, as in the separation of the electrons and holes in superconductors. In the electron-hole case, the symmetry operator is [[-1,0],[0,1]]. There are two eigenvalues (+1, -1) and the eigenvalues are different. Can the kwant code be used to handle a symmetry operator like [[0,0,0,0],[0,0,0,0],[0,0,1,0],[0,0,0,1]]. There are four eigenvalues in two degenerate pairs. This is like a system with four orbitals in a unit cell and each pair of orbitals have the same energy. There are two possible scenario. With this symmetry operator, the lead Hamiltonian is block diagonalized into two blocks. Can the conservation law function handle this case? What would happen if the hopping can split the degenerate eigenvalues within a single block? Can the conservation law function handle this case too?

 

KS Chan