Dear Mohamed, it seems that you have defined your bilayer lattice in 3d. If so you have to avoid using the z-axis in your system. For the current you need to define a lattice as 2d shape (ie x and y axis for instance). >From the tight binding side, it does not matter if one sets two layers on each other (ie z=0 for boath) and then adds the hopping between each layer. I hope this helps, otherwise it would be great if you share your script to find out the issue. Best, Adel
Le lun. 12 juil. 2021 à 12:44, <[email protected]> a écrit : > Dear all, > I have written a code in Kwant for a bilayer graphene quantum dot (in 2D > manner) to calculate some electronic properties. > I can get the results correctly for, e.g, conductance, spectrum, and LDOS. > But there is a problem in plotting CURRENT density and I get the following > error. > > ~~ need at least one array to concatenate > > Has anyone had a similar experience ? > The current density part of code is: > ________________________________________________________________ > ### Current plot > params = dict(B=Bfield, r0=[0,0], h0=0) > wf = kwant.wave_function(syst, energy=0.01, params=params) > psi = wf(0)[0] > > J_0 = kwant.operator.Current(syst) > current = J_0(psi, params=params) > kwant.plotter.current(syst, current) > _________________________________________________________________ >
