Remove function for outer product of self-energies

adga.py

@@ -187,21 +187,3 @@ class Adga(object):
         output_file.close()
         susceptibilities = np.array(susceptibilities)
         return susceptibilities[:, 0, 0, :, :, 0, :]
-
-
-def outer_product_of_self_energies(a, b):
-    """Return the outer product of ``a`` and ``b`` in the frequency
-    index.
-    
-    :arg a: self-energy as 3D numpy array
-    :arg b: self-energy as 3D numpy array
-    :return: 4D numpy array :math:`c_{(i)(j)kl}=a_{(i)(j)k}b_{(i)(j)l}`
-    """
-    
-    result_shape = list(a.shape)
-    result_shape.append(a.shape[-1])
-    result = np.empty(result_shape)
-    for i in range(len(a)):
-        for j in range(len(a[0])):
-            result[i, j] = np.outer(a[i, j, :], np.conjugate(b[i, j, :]))
-    return result