fix plots sticking together

code/band_structures.py

@@ -72,6 +72,7 @@ def phonons_1d():
 
 
 def tight_binding_1d():
+    pyplot.figure()
     k = np.linspace(-pi, pi, 300)
     pyplot.plot(k, -np.cos(k))
     pyplot.xlabel('$ka$'); pyplot.ylabel('$E$')