diff --git a/Final/Final - Tight-binding propagation method.ipynb b/Final/Final - Tight-binding propagation method.ipynb
index e0f4c61..d454443 100644
--- a/Final/Final - Tight-binding propagation method.ipynb	
+++ b/Final/Final - Tight-binding propagation method.ipynb	
@@ -623,21 +623,21 @@
    },
    "outputs": [],
    "source": [
-    "def hopping(i, j, n):\n",
+    "def hopping(i, j, n, sigma=.25):\n",
     "    \"\"\"\n",
     "    Calculates hopping matrix elements t_ij for sigma = 0.25 in a 1D\n",
     "    chain of n atoms at distance a = 1 from eachother.\n",
     "    \n",
     "    Args:\n",
-    "        i: origin site index\n",
-    "        j: destination site index\n",
-    "        n: number of atoms in the chain\n",
+    "        i:     origin site index\n",
+    "        j:     destination site index\n",
+    "        n:     number of atoms in the chain\n",
+    "        sigma: standard deviation to the Gaussian wave functions\n",
     "\n",
     "    Returns:\n",
     "        Hopping parameter t_ij.\n",
     "    \"\"\"\n",
     "    \n",
-    "    sigma = .25\n",
     "    positions = atomic_positions(n)\n",
     "    \n",
     "    # This 'infinity' is large enough, as the Gaussians decay quite quickly\n",