Update src/7_tight_binding_model_sol.md

src/7_tight_binding_model_sol.md

@@ -36,6 +36,6 @@ 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([1], [r'$2\sqrt{\frac{\kappa}{m}}$'])
+pyplot.yticks([0, 1], [0, r'$2\sqrt{\frac{\kappa}{m}}$'])
 pyplot.hlines([1], -pi/2, 0, linestyles='dashed')
 ```