quantum_well.py.diff

@@ -1,88 +1,95 @@
 # Tutorial 2.3.2. Spatially dependent values through functions
 # ============================================================
 #
 # Physics background
 # ------------------
 #  transmission through a quantum well
 #
 # Kwant features highlighted
 # --------------------------
 #  - Functions as values in Builder
 
+import _defs
 import kwant
 
 # For plotting
 from matplotlib import pyplot
 
 
 #HIDDEN_BEGIN_ehso
 def make_system(a=1, t=1.0, W=10, L=30, L_well=10):
     # Start with an empty tight-binding system and a single square lattice.
     # `a` is the lattice constant (by default set to 1 for simplicity.
     lat = kwant.lattice.square(a)
 
     syst = kwant.Builder()
 
     #### Define the scattering region. ####
     # Potential profile
     def potential(site, pot):
         (x, y) = site.pos
         if (L - L_well) / 2 < x < (L + L_well) / 2:
             return pot
         else:
             return 0
 #HIDDEN_END_ehso
 
 #HIDDEN_BEGIN_coid
     def onsite(site, pot):
         return 4 * t + potential(site, pot)
 
     syst[(lat(x, y) for x in range(L) for y in range(W))] = onsite
     syst[lat.neighbors()] = -t
 #HIDDEN_END_coid
 
     #### Define and attach the leads. ####
     lead = kwant.Builder(kwant.TranslationalSymmetry((-a, 0)))
     lead[(lat(0, j) for j in range(W))] = 4 * t
     lead[lat.neighbors()] = -t
     syst.attach_lead(lead)
     syst.attach_lead(lead.reversed())
 
     return syst
 
 
 def plot_conductance(syst, energy, welldepths):
 #HIDDEN_BEGIN_sqvr
 
     # Compute conductance
     data = []
     for welldepth in welldepths:
         smatrix = kwant.smatrix(syst, energy, params=dict(pot=-welldepth))
         data.append(smatrix.transmission(1, 0))
 
-    pyplot.figure()
+    fig = pyplot.figure()
     pyplot.plot(welldepths, data)
-    pyplot.xlabel("well depth [t]")
-    pyplot.ylabel("conductance [e^2/h]")
-    pyplot.show()
+    pyplot.xlabel("well depth [t]",
+                 fontsize=_defs.mpl_label_size)
+    pyplot.ylabel("conductance [e^2/h]",
+                 fontsize=_defs.mpl_label_size)
+    pyplot.setp(fig.get_axes()[0].get_xticklabels(),
+               fontsize=_defs.mpl_tick_size)
+    pyplot.setp(fig.get_axes()[0].get_yticklabels(),
+               fontsize=_defs.mpl_tick_size)
+    fig.set_size_inches(_defs.mpl_width_in, _defs.mpl_width_in * 3. / 4.)
+    fig.subplots_adjust(left=0.15, right=0.95, top=0.95, bottom=0.15)
+    for extension in ('pdf', 'png'):
+        fig.savefig("quantum_well_result." + extension, dpi=_defs.dpi)
 #HIDDEN_END_sqvr
 
 
 def main():
     syst = make_system()
 
-    # Check that the system looks as intended.
-    kwant.plot(syst)
-
     # Finalize the system.
     syst = syst.finalized()
 
     # We should see conductance steps.
     plot_conductance(syst, energy=0.2,
                      welldepths=[0.01 * i for i in range(100)])
 
 
 # Call the main function if the script gets executed (as opposed to imported).
 # See <http://docs.python.org/library/__main__.html>.
 if __name__ == '__main__':
     main()