diff --git a/src/geometry/backbone.py b/src/geometry/backbone.py
index bacfa18..33725a0 100644
--- a/src/geometry/backbone.py
+++ b/src/geometry/backbone.py
@@ -1,23 +1,25 @@
-
-# Ideal geometry. Angstroms for lengths, degrees for angles.
+import numpy as np
+# Ideal geometry. Angstroms for lengths, degrees for angles. Engh & Huber parameters
 GEO = {
-    'N_CA_len': 1.46,
-    'CA_C_len': 1.51,
-    'C_N_len':  1.33, 
-    'N_H_len':  1.01,  
+    'N_CA_length': 1.46,
+    'CA_C_length': 1.51,
+    'C_N_length':  1.33, 
+    'N_H_length':  1.01,  
+    'C_O_length': 1.23,
 
     'N_CA_C_angle': 111.0,
     'CA_C_N_angle': 116.0, 
     'C_N_CA_angle': 122.0,
     'C_N_H_angle': 119.0, 
+    'CA_C_O_angle': 121.0,
 }
 
 # First residue backbone hardcoded. From 6G4A MET1
 ORI = {
-     'N': [ -17.396, -12.153, -13.987 ],
-    'CA': [ -16.295, -12.486, -13.259 ],
-     'C': [ -16.534, -10.993, -13.428 ],
-     'O': [ -16.891, -10.572, -14.520 ],
+     'N': np.array([ -17.396, -12.153, -13.987 ]),
+    'CA': np.array([ -16.295, -12.486, -13.259 ]),
+     'C': np.array([ -16.534, -10.993, -13.428 ]),
+     'O': np.array([ -16.891, -10.572, -14.520 ]),
 }
 
 if __name__ == "__main__":