update

academic_codes/2021.02.08_quantum_transport_in_multi_lead_systems/quantum_transport_in_multi_lead_systems_with_kwant.py

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+"""
+This code is supported by the website: https://www.guanjihuan.com
+The newest version of this code is on the web page: https://www.guanjihuan.com/archives/6075
+"""
+
+import kwant
+import numpy as np
+from matplotlib import pyplot
+
+def make_system():
+    a = 1
+    lat = kwant.lattice.square(a)
+    syst = kwant.Builder()
+    t = 1.0
+    W = 5
+    L = 50
+    syst[(lat(x, y) for x in range(L) for y in range(W))] = 0
+    syst[lat.neighbors()] = -t  
+    #   几何形状如下所示：
+    #               lead2         lead3
+    #   lead1(L)                          lead4(R)  
+    #               lead6         lead5
+    lead1 = kwant.Builder(kwant.TranslationalSymmetry((-a, 0)))
+    lead1[(lat(0, j) for j in range(W))] = 0
+    lead1[lat.neighbors()] = -t
+    syst.attach_lead(lead1) 
+
+    lead2 = kwant.Builder(kwant.TranslationalSymmetry((0, -a)))
+    lead2[(lat(j, 0) for j in range(W))] = 0
+    lead2[lat.neighbors()] = -t  
+    syst.attach_lead(lead2) 
+
+    lead3 = kwant.Builder(kwant.TranslationalSymmetry((0, -a)))
+    lead3[(lat(j+(L-W), 0) for j in range(W))] = 0
+    lead3[lat.neighbors()] = -t  
+    syst.attach_lead(lead3) 
+
+    syst.attach_lead(lead1.reversed())   # lead4
+    syst.attach_lead(lead3.reversed())   # lead5
+    syst.attach_lead(lead2.reversed())   # lead6
+
+    kwant.plot(syst) 
+    syst = syst.finalized() 
+    return syst
+
+
+def main():
+    syst = make_system()
+    energies = np.linspace(-4, 4, 800)
+    data1 = []
+    data2 = []
+    data3 = []
+    data4 = []
+    data5 = []
+    data6 = []
+    for energy in energies:
+        smatrix = kwant.smatrix(syst, energy)  
+        data1.append(smatrix.transmission(1, 0))   # compute the transmission probability from lead 0 to lead 1
+        data2.append(smatrix.transmission(2, 0))
+        data3.append(smatrix.transmission(3, 0))
+        data4.append(smatrix.transmission(4, 0))
+        data5.append(smatrix.transmission(5, 0))
+        data6.append(smatrix.transmission(1, 0)+smatrix.transmission(2, 0)+smatrix.transmission(3, 0)+smatrix.transmission(4, 0)+smatrix.transmission(5, 0))
+    pyplot.plot(energies, data1)
+    pyplot.xlabel("energy [t]")
+    pyplot.ylabel("Transmission_12 [e^2/h]")
+    pyplot.show()
+    pyplot.plot(energies, data2)
+    pyplot.xlabel("energy [t]")
+    pyplot.ylabel("Transmission_13 [e^2/h]")
+    pyplot.show()
+    pyplot.plot(energies, data3)
+    pyplot.xlabel("energy [t]")
+    pyplot.ylabel("Transmission_14 [e^2/h]")
+    pyplot.show()
+    pyplot.plot(energies, data4)
+    pyplot.xlabel("energy [t]")
+    pyplot.ylabel("Transmission_15 [e^2/h]")
+    pyplot.show()
+    pyplot.plot(energies, data5)
+    pyplot.xlabel("energy [t]")
+    pyplot.ylabel("Transmission_16 [e^2/h]")
+    pyplot.show()
+    pyplot.plot(energies, data6)
+    pyplot.xlabel("energy [t]")
+    pyplot.ylabel("Transmission_1_all [e^2/h]")
+    pyplot.show()
+
+
+if __name__ == '__main__':
+    main()