Merge branch 'master' into local

src/1_einstein_model.md

@@ -263,7 +263,7 @@ ax2.set_ylabel(r"$\langle E \rangle$")
 ax2.set_yticks([1/2])
 ax2.set_yticklabels([r'$\hbar\omega_0/2$'])
 draw_classic_axes(ax2, xlabeloffset=.15)
-ax.text(1.05, 0.95, r'$k_{\rm B}T=\hbar \omega_0 =$', ha='left', color='r');
+ax2.text(1.05, 0.95, r'$k_{\rm B}T=\hbar \omega_0 =$', ha='left', color='r');
 ```
 
 We now calculate the heat capacity per atom $C$ explicitly. To do so, we need to differentiate $\langle E \rangle$ with respect to $T$.