From a93e150ba63893428021168adb8b389444ba6955 Mon Sep 17 00:00:00 2001
From: Lars kleyn Winkel <l.kleynwinkel@student.tudelft.nl>
Date: Mon, 10 Feb 2020 15:46:00 +0000
Subject: [PATCH] Update src/7_tight_binding_model_sol.md
---
src/7_tight_binding_model_sol.md | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/7_tight_binding_model_sol.md b/src/7_tight_binding_model_sol.md
index 5534bff9..ca5067e8 100644
--- a/src/7_tight_binding_model_sol.md
+++ b/src/7_tight_binding_model_sol.md
@@ -35,8 +35,8 @@ Group velocity is given as $v=\hbar^{-1}\frac{\partial E}{\partial k}$ with $E=\
```python
pyplot.subplot(1,2,1)
-k = np.linspace(-pi/2, pi/2, 300)
-pyplot.plot(k, np.cos(k));
+k = np.linspace(-pi/2+0.01, pi/2-0.01, 300)
+pyplot.plot(k, np.sin(k)/(np.sqrt(1-np.cos(k)));
pyplot.xlabel('$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'$2\sqrt{\frac{\kappa}{m}}$']);
--
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