Dear kwant users I'm trying to calculate magnetic field dependent conductance of a system. For this I used the scattering matrix and adding temperature dependence by multiplying the transmission value by the derivative of the fermi-dirac function. Because of the results I got, I'm not sure if this is the right way of doing it. Can someone please help me? Thank you very much Best regards Simon Code: fluxes = np.linspace(0, 5, 100) def make_system(a=1, t=1.5, w=15, d=30): lat = kwant.lattice.square(a) syst = kwant.Builder() def onsite(site, U0, salt): return U0 * (uniform(repr(site), repr(salt)) - 0.5) + 4*t syst[(lat(x, y) for x in range(w) for y in range(d))] = onsite def hopping(site_i, site_j, phi): xi, yi = site_i.pos xj, yj = site_j.pos if yi == yj: return -t if xi == xj: return -0.001 * t * exp(-0.5j * phi * (xi + xj) * (yi - yj)) syst[lat.neighbors()] = hopping lead = kwant.Builder(kwant.TranslationalSymmetry((0, -a))) lead[(lat(j, 0) for j in range(w))] = 4 * t lead[lat.neighbors()] = hopping syst.attach_lead(lead) syst.attach_lead(lead.reversed()) return syst def plot_conductance(syst): temp = 0.01 w=15 d=30 U0=0 salt = 0.2 phis = np.linspace(0, (2 * pi / w) * 5, 100) count = 0 values = [] for phi in phis: count += 1 ham_mat = syst.hamiltonian_submatrix(params=dict(phi=phi, U0=U0, salt=salt), sparse=True) evals = np.real(np.sort(np.linalg.eigvals(ham_mat.todense()))) EF = evals[int(len(evals) / 2)] liste = [] for k in range(0,len(evals)): energy = evals[k] if EF-temp <= energy <= EF+temp: df = np.real(exp((energy - EF) / temp) / (temp * (exp((energy - EF) / temp) + 1) ** 2)) Smatrix = kwant.smatrix(syst, energy, params=dict(phi=phi, U0=U0, salt=salt)) liste.append(Smatrix.transmission(0,1)*df) val = sum(liste)/(len(liste)) values.append(val/(w*d)) print(count) plt.plot(fluxes,values, label = w) plt.grid(True) plt.title("Conductance eqhop temp=0.1") plt.legend() plt.ylabel("G_[G_0]") plt.xlabel(r'$\phi [2\pi / L]$') plt.show() def main(): syst = make_system() syst = syst.finalized() plot_conductance(syst) if __name__ == "__main__": main()