diff --git a/Final/Final - Tight-binding propagation method.ipynb b/Final/Final - Tight-binding propagation method.ipynb
index dc2eeec..6139513 100644
--- a/Final/Final - Tight-binding propagation method.ipynb	
+++ b/Final/Final - Tight-binding propagation method.ipynb	
@@ -610,8 +610,14 @@
    "outputs": [],
    "source": [
     "def hopping(i, j, n):\n",
-    "    # YOUR CODE HERE\n",
-    "    raise NotImplementedError()\n",
+    "    \"\"\"\n",
+    "    \n",
+    "    \"\"\"\n",
+    "    \n",
+    "    x = np.linspace(-1e12, 1e12, 1e12)\n",
+    "    V = lambda x: -1 \n",
+    "    integrand = lambda x: atomic_basis(x, positions[i], sigma)*V(x)*atomic_basis(x, positions[j], sigma)\n",
+    "    return integrate(integrand, x)\n",
     "\n",
     "# Yann had\n",
     "# 1) a plot of the peaks as before\n",