Update src/7_tight_binding_model_sol.md

src/7_tight_binding_model_sol.md

@@ -34,13 +34,12 @@ Group velocity is given as $v=\hbar^{-1}\frac{\partial E}{\partial k}$ with $E=\
 3.
 
 ```python
-##pyplot.subplot(1,2,1)
-##k = np.linspace(-pi/2, pi/2, 300)
-##pyplot.plot(k, np.cos(k))
-##pyplot.xlabel('$k$'); pyplot.ylabel('$v(k)$')
-##pyplot.xticks([-pi/2, 0, pi/2], [r'$-\pi/2$', 0, r'$\pi/2$'])
-##pyplot.yticks([0, 1], [0, r'$2\sqrt{\frac{\kappa}{m}}$'])
-##pyplot.hlines([1], -pi/2, 0, linestyles='dashed')
+pyplot.subplot(1,2,1)
+k = np.linspace(-pi/2, pi/2, 300)
+pyplot.plot(k, np.cos(k))
+pyplot.xlabel('$k$'); pyplot.ylabel('$v(k)$')
+pyplot.xticks([-pi/2, 0, pi/2], [r'$-\pi/2$', 0, r'$\pi/2$'])
+pyplot.yticks([0, 1], [0, r'$2\sqrt{\frac{\kappa}{m}}$'])
 
 pyplot.subplot(1,2,2)
 w = np.linspace(-0.95, 0.95, 300)
@@ -48,8 +47,7 @@ g = 1/np.sqrt(1-w**2)
 pyplot.plot(w, g)
 pyplot.xlabel(r'$\omega$'); pyplot.ylabel('$g(w)$')
 pyplot.xticks([-1, 0, 1], [r'$-2\sqrt{\frac{k}{m}}$', 0, r'$2\sqrt{\frac{k}{m}}$'])
-pyplot.yticks([0, 1], [0, r'$\frac{L}{2\pi a}\sqrt{\frac{\kappa}{m}}$'])
-pyplot.hlines([1], -pi/2, 0, linestyles='dashed')
+pyplot.yticks([0.5, 1], [0, r'$\frac{L}{2\pi a}\sqrt{\frac{\kappa}{m}}$'])
 ```
 
 4.