New module with stand-alone functions for computation of expected values

doc/source/api-reference/qibo.rst

@@ -1375,6 +1375,17 @@ Heisenberg XXZ
     This is useful for systems that contain many qubits for which constructing
     the full matrix is intractable.
 
+
+Expectation values
+^^^^^^^^^^^^^^^^^^
+
+Functions to compute expectation values of Hamiltonians expressed in different input formats.
+
+Expectation values of Hamiltonians
+""""""""""""""""""""""""""""""""""
+
+.. autofunction:: qibo.hamiltonians.expectation_values.get_expval_hamiltonian
+
 _______________________