Dear everyone: we know that enegy gap in Landau levels is hw, then we can know the magnitude of magnatic field by claculating the gap between landau levels, in this code, the magnitude of magnetic field I set is way different by calculating the energy gap in Landau levels in this code, Ihave no idea what went wrong, so I'll be thankful if you can konw what is wrong in this code. Thank you Following is my code—-————————————————- ### Import modules ### import kwant import numpy as np from math import pi from matplotlib import pyplot as plt import csv import scipy.sparse.linalg as sla a = 1 # Lattice constant, in nm h = 4.14e-15 # Plank's constnt in unit of eV*s hbar = 6.58e-16 # In unit of eV*s m = 9.11e-31 # Mass of electron in kg q = 1.6e-19 # Charge of an electron in coulomb t = hbar*hbar/(2*m*a*a) # t = hbar^2/(2m(a^2)) B = 3 # Magnitude of external magnetic field, in unit of Tesla phi0 = 4.14e-15 # Magnetic quantum def setup_system(W=100, L=100): ### Define a function about hopping ### def hopping(hop): x1, y1 = hop[0].pos # Get the position imformation of site_1 x2, y2 = hop[1].pos # Get the position imformation of site_2 delta_x = (x2 - x1) * 1e-9 # Differance of x coordinate in nanometer y_bar = (y1 + y2) / 2 * 1e-9 # Averge of y coordinate in nanometer return delta_x, y_bar ### Define the shape of the system ### def rectangle(pos): x, y = pos return x > -W and x < W and y > -L and y < L ### Define the shape of the lead ### def lead_shape(pos): x, y = pos return (-L < y < L) ### Set up the system ### sys = kwant.Builder() # Builde up the system lat = kwant.lattice.square(a, norbs = 1) # Set up the lattice in shape of square sys[lat.shape(rectangle, (0, 0))] = 4 * t # Define the on-site energy for hopx in kwant.builder.HoppingKind((1, 0), lat)(sys): # Define the hopping in x-direction delta_x, y_bar = hopping(hopx) phase = 2* pi /phi0 *B *delta_x *y_bar # Phase differnce due to magnetic field sys[hopx] = -t * np.exp( phase*1j) for hopy in kwant.builder.HoppingKind((0, 1), lat)(sys): # Define the hopping in y-direction sys[hopy] = -t ### Set up the left lead ### lead0 = kwant.Builder(kwant.TranslationalSymmetry((-1, 0))) # The current goes from the left lead lead0[lat.shape(lead_shape, (0, 0))] = 4 * t # Define the on-site energy for hopx in kwant.builder.HoppingKind((1, 0), lat)(lead0): # Define the hopping in x-direction delta_x, y_bar = hopping(hopx) phase = 2* pi /phi0 *B *delta_x *y_bar # Phase differnce due to magnetic field lead0[hopx] = -t * np.exp( phase*1j) for hopy in kwant.builder.HoppingKind((0, 1), lat)(lead0): # Define the hopping in y-direction lead0[hopy] = -t ### Set up the right lead ### lead1 = kwant.Builder(kwant.TranslationalSymmetry((1, 0))) # The current goes from the left lead lead1[lat.shape(lead_shape, (0, 0))] = 4 * t # Define the on-site energy for hopx in kwant.builder.HoppingKind((1, 0), lat)(lead1): # Define the hopping in x-direction delta_x, y_bar = hopping(hopx) phase = 2* pi /phi0 *B *delta_x *y_bar # Phase differnce due to magnetic field lead1[hopx] = -t * np.exp( phase*1j) for hopy in kwant.builder.HoppingKind((0, 1), lat)(lead1): # Define the hopping in y-direction lead1[hopy] = -t ### Attach the left lead and the right lead ### sys.attach_lead(lead0) sys.attach_lead(lead1) ### Finalize the system ### sys = sys.finalized() ### Finally, return the system ### return sys sys = setup_system() ### Compute, plot and store the bandstructure ### def plot_bandstructure(flead, momenta): bands = kwant.physics.Bands(flead) energies = [bands(k)[0: 10] for k in momenta] bandenergy = [] '''np.savetxt("Momentatest_l.csv", momenta, delimiter = ",") for i in range(1000): bandenergy.append(energies[i]) np.savetxt("Band_energytest1_l.csv", bandenergy, delimiter = ",")''' plt.figure(figsize=(6, 8)) plt.plot(momenta, energies, color='k') plt.xlabel("momentum [a^-1]") plt.ylabel("energy [eV]") plt.ylim(0, 0.03) plt.xlim(-1, 1) plt.show() #kwant.plotter.bands(sys.leads[0]) momenta = np.linspace(-1, 1, 1000) plot_bandstructure(sys.leads[0], momenta) plot_bandstructure(sys.leads[1], momenta)