bugfix: make args and kwargs work for bandstructure calculations

kwant/physics/dispersion.py

@@ -20,6 +20,10 @@ class Bands(object):
     sys : `kwant.system.InfiniteSystem`
         The low level infinite system for which the energies are to be
         calculated.
+    args : tuple, defaults to empty
+        Positional arguments to pass to the ``hamiltonian`` method.
+    kwargs : dictionary, defaults to empty
+        Keyword arguments to pass to the ``hamiltonian`` method.
 
     Notes
     -----
@@ -37,11 +41,11 @@ class Bands(object):
     >>> pyplot.show()
     """
 
-    def __init__(self, sys):
-        self.ham = sys.slice_hamiltonian()
+    def __init__(self, sys, args=(), kwargs={}):
+        self.ham = sys.slice_hamiltonian(args=args, kwargs=kwargs)
         if not np.allclose(self.ham, self.ham.T.conj()):
             raise ValueError('The slice Hamiltonian is not Hermitian.')
-        hop = sys.inter_slice_hopping()
+        hop = sys.inter_slice_hopping(args=args, kwargs=kwargs)
         self.hop = np.empty(self.ham.shape, dtype=complex)
         self.hop[:, : hop.shape[1]] = hop
         self.hop[:, hop.shape[1]:] = 0

kwant/plotter.py

@@ -850,13 +850,18 @@ def map(sys, value, colorbar=True, cmap=None,
     return output_fig(fig, file=file, show=show)
 
 
-def bands(sys, momenta=65, file=None, show=True, dpi=None, fig_size=None):
+def bands(sys, momenta=65, args=(), kwargs={},
+          file=None, show=True, dpi=None, fig_size=None):
     """Plot band structure of a translationally invariant 1D system.
 
     Parameters
     ----------
     sys : kwant.system.InfiniteSystem
         A system bands of which are to be plotted.
+    args : tuple, defaults to empty
+        Positional arguments to pass to the ``hamiltonian`` method.
+    kwargs : dictionary, defaults to empty
+        Keyword arguments to pass to the ``hamiltonian`` method.
     momenta : int or 1D array-like
         Either a number of sampling points on the interval [-pi, pi], or an
         array of points at which the band structure has to be evaluated.
@@ -885,7 +890,7 @@ def bands(sys, momenta=65, file=None, show=True, dpi=None, fig_size=None):
     if momenta.ndim != 1:
         momenta = np.linspace(-np.pi, np.pi, momenta)
 
-    bands = physics.Bands(sys)
+    bands = physics.Bands(sys, args=args, kwargs=kwargs)
     energies = [bands(k) for k in momenta]
 
     fig = Figure()