Added examples for vibrational Hamiltonian functions

pennylane/bose/bosonic_mapping.py

@@ -334,6 +334,15 @@ def christiansen_mapping(
 
     Returns:
         Union[PauliSentence, Operator]: A linear combination of qubit operators.
+
+    **Example**
+
+    >>> w = qml.bose.BoseWord({(0,0):"+", (1,1): "-"})
+    >>> qml.christiansen_mapping(w)
+    0.25 * (X(0) @ X(1))
+    + 0.25j * (X(0) @ Y(1))
+    + -0.25j * (Y(0) @ X(1))
+    + (0.25+0j) * (Y(0) @ Y(1))
     """
 
     qubit_operator = _christiansen_mapping_dispatch(bose_operator, tol)

pennylane/qchem/vibrational/localize_modes.py

@@ -195,6 +195,22 @@ def localize_normal_modes(freqs, vecs, bins=[2600]):
          - TensorLike[float] : localization matrix describing the relationship between
            original and localized modes.
 
+    **Example**
+
+    >>> freqs = [1326.66001461, 2297.26736859, 2299.65032901]]
+    >>> vectors = [[[ 5.71518696e-18, -4.55642350e-01,  5.20920552e-01],
+                    [ 1.13167924e-17,  4.55642350e-01,  5.20920552e-01],
+                    [-1.23163569e-17,  5.09494945e-12, -3.27565762e-02]],
+                   [[-4.53008817e-17,  4.90364125e-01,  4.90363894e-01],
+                    [-1.98591028e-16,  4.90361513e-01, -4.90361744e-01],
+                    [-2.78235498e-18, -3.08350419e-02, -6.75886679e-08]],
+                   [[ 5.75393451e-17,  5.37047963e-01,  4.41957355e-01],
+                    [ 6.53049347e-17, -5.37050348e-01,  4.41959740e-01],
+                    [-5.49709883e-17,  7.49851221e-08, -2.77912798e-02]]]
+    >>> freqs_loc, vecs_loc, uloc = qml.qchem.localize_normal_modes(freqs, vectors)
+    >>> freqs_loc
+    [1332.62021421, 2296.73451756, 2296.73457617]
+
     """
     if not bins:
         raise ValueError("The `bins` list cannot be empty.")

pennylane/qchem/vibrational/vibrational_class.py

@@ -40,6 +40,28 @@ class VibrationalPES:
             1, 2, or 3 for upto one-mode dipole, two-mode dipole and three-mode dipole, respectively. Default
             value is 1.
 
+    **Example**
+
+    >>> freqs = np.array([0.01885397])
+    >>> grid, weights = np.polynomial.hermite.hermgauss(9)
+    >>> pes_onebody = [[0.05235573, 0.03093067, 0.01501878, 0.00420778, 0.0,
+                        0.00584504, 0.02881817, 0.08483433, 0.22025702]]
+    >>> pes_twobody = None
+    >>> dipole_onebody = [[[-1.92201700e-16,  1.45397041e-16, -1.40451549e-01],
+                           [-1.51005108e-16,  9.53185441e-17, -1.03377032e-01],
+                           [-1.22793018e-16,  7.22781963e-17, -6.92825934e-02],
+                           [-1.96537436e-16, -5.86686504e-19, -3.52245369e-02],
+                           [ 0.00000000e+00,  0.00000000e+00,  0.00000000e+00],
+                           [ 5.24758835e-17, -1.40650833e-16,  3.69955543e-02],
+                           [-4.52407941e-17,  1.38406311e-16,  7.60888733e-02],
+                           [-4.63820104e-16,  5.42928787e-17,  1.17726042e-01],
+                           [ 1.19224372e-16,  9.12491386e-17,  1.64013197e-01]]]
+    >>> vib_obj = qml.qchem.VibrationalPES(freqs=freqs, grid=grid, gauss_weights=weights,
+                                 uloc = None, pes_data=[pes_onebody, pes_twobody],
+                                 dipole_data=[dipole_onebody], localized=False)
+    >>> vib_obj.freqs
+    [0.01885397]
+
     """
 
     def __init__(
@@ -150,6 +172,17 @@ def optimize_geometry(molecule, method="rhf"):
     Returns:
         array[array[float]]: optimized atomic positions in Cartesian coordinates
 
+    **Example**
+
+    >>> symbols  = ['H', 'F']
+    >>> geometry = np.array([[0.0, 0.0, 0.0],
+                            [0.0, 0.0,  1.0]])
+    >>> mol = qml.qchem.Molecule(symbols, geometry)
+    >>> eq_geom = qml.qchem.optimize_geometry(mol)
+    >>> eq_geom
+    [[0.0, 0.0, -0.40277116],
+     [0.0, 0.0,  1.40277116]]
+
     """
     pyscf = _import_pyscf()
     geometric = _import_geometric()