Add general Heisenberg Hamiltonian and XXX model

doc/source/api-reference/qibo.rst

@@ -1267,13 +1267,6 @@ In addition to the abstract Hamiltonian models, Qibo provides the following
 pre-coded Hamiltonians:
 
 
-Heisenberg XXZ
-^^^^^^^^^^^^^^
-
-.. autoclass:: qibo.hamiltonians.XXZ
-    :members:
-    :member-order: bysource
-
 Non-interacting Pauli-X
 ^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -1326,6 +1319,30 @@ Max Cut
     This is useful for systems that contain many qubits for which constructing
     the full matrix is intractable.
 
+
+Heisenberg model
+^^^^^^^^^^^^^^^^
+
+.. autoclass:: qibo.hamiltonians.Heisenberg
+    :members:
+    :member-order: bysource
+
+
+Heisenberg XXX
+^^^^^^^^^^^^^^
+
+.. autoclass:: qibo.hamiltonians.XXX
+    :members:
+    :member-order: bysource
+
+
+Heisenberg XXZ
+^^^^^^^^^^^^^^
+
+.. autoclass:: qibo.hamiltonians.XXZ
+    :members:
+    :member-order: bysource
+
 _______________________
 
 

src/qibo/hamiltonians/__init__.py

@@ -1,2 +1,6 @@
-from qibo.hamiltonians.hamiltonians import *
-from qibo.hamiltonians.models import TFIM, XXZ, MaxCut, X, Y, Z
+from qibo.hamiltonians.hamiltonians import (
+    Hamiltonian,
+    SymbolicHamiltonian,
+    TrotterHamiltonian,
+)
+from qibo.hamiltonians.models import TFIM, XXX, XXZ, Heisenberg, MaxCut, X, Y, Z