Hi again, I just realized that my example was kind of broken as I defined a a variable `mode` and then promptly overwrote this with something else. The examples should have read as follows:: lead = 1 # whatever mode = 0 # whatever smatrix = kwant.smatrix(sys, energy) modes = smatrix.lead_info sites = fsys.leads[lead].sites psi = modes[lead].wave_functions[:, mode] psi = dict(zip(sites, psi)) and:: sites = fsys.leads[lead].sites psi = modes[lead].wave_functions[:, mode] psi_up = dict(zip(sites, psi[::2])) # even elements of psi (up) psi_down = dict(zip(sites, psi[1::2])) # odd elements of psi (down) Regards, Joe