Update 4_sommerfeld_model.md

src/4_sommerfeld_model.md

@@ -35,7 +35,7 @@ $$
 
 ```python
 kf = 3;
-extrapol = 1.2;
+extrapol = 1.1;
 ks = np.arange(-kf, kf+1);
 kcont = np.linspace(-extrapol*kf, extrapol*kf, 1000);
 
@@ -54,10 +54,10 @@ ax.set_ylim(0.0, 11);
 ax.set_xlabel(r"$k \quad \left[ \frac{2 \pi}{L} \right]$");
 ax.set_ylabel(r"$\varepsilon$");
 
-ax.set_xticklabels(ks);
-
+ax.set_xticklabels([""] + ks + [""]);
 ax.set_yticks([]);
-draw_classic_axes(ax, xlabeloffset=.2);
+
+draw_classic_axes(ax, xlabeloffset=.6);
 ```
 
 Comparable to phonons, but: electrons are _fermions_.